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One K Defender Matte Helmet

One K
- Item #21807
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We're bringing you this product at the lowest price allowed by the manufacturer. That means this item isn't eligible for additional discounts or promotions.

As riders and online shoppers, we know it can be tough to buy a new bridle or pair of boots without trying them on. That's why we moved the fitting room to your living room (or barn)! From breeches to blankets, if you or your horse can try it on, you can return it, free! Just use the pre-paid return label included in your order within 60 days from the purchase date. And of course, please make sure the item is in like-new condition with original packaging (we said 'fitting room', not 'war room'!).

Why We Love This

The One K Defender Matte Helmet is sure to keep you cool with two side, two front, one back, and two center stripe vents! This all-around stylish helmet is great for both schooling and showing in a number of different disciplines!

Favorite Features

  • Polycarbonate and Advanced ABS Composite outer shell with an injection molded shell design
  • Inner lining is anti-microbial, moisture wicking, quick drying, and washable
  • Stainless steel mesh
  • Comfort padded harness with synthetic suede lining and Fastex buckle


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    95% of customers would recommend this product to a friend!
    Tell us what you think!

    SmartPak customers are some of the most conscientious animal owners around. We encourage you to share your experience with the products we sell to help fellow customers to make informed choices for their animals. We do not edit these reviews in any way - they are direct customer-to-customer communication. We do monitor reviews for positive and negative feedback, and use this feedback to improve our selection as well as sharing feedback with product manufacturers to help them improve their products. Please note that we recommend consulting your vet with serious health issues.

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    One K Defender Matte Helmet is rated 4.6744 out of 5 by 43.
    Rated 4 out of 5 by from attractive and lightweight I wear this to polo practice and it's very nice looking and lightweight. It is a little tight and gives me a headache after too long, I think I just need to break the padding in as the next size up would be too big. I like that the chin strap comes forward a little more and doesn't give you a double chin look like some helmets!
    Date published: 2015-08-24
    Rated 5 out of 5 by from Great Helmet Lightweight and has good ventilation, I can actually feel the air flow through the top of the helmet. The liner could be more padded, but the helmet is still comfortable when you're wearing it. The chin strap is a little more forward than most other helmets but when adjusted properly it is still secure and comfortable. The Velcro on the harness is nice in that it eliminates the look of extra straps dangling, giving a nice polished look. Liner is easy to remove and install, haven't tried washing it. Overall, this helmet has all the same features of the Samshield (and more ventilation) at half the cost. I use mine for schooling but I have seen them gaining some popularity in the hunter/jumper show rings. For reference, I wear a 6 7/8 in a CO JR8 and the size Medium fit, but just barely. It was uncomfortably snug to start but after wearing it several times the liner has compressed and it is now comfortable.
    Date published: 2015-08-12
    Rated 5 out of 5 by from Versatile Helmet at good price My old helmet was past the 5 year mark, and per manufacturer recommendations it needed replaced. I had purchased the same helmet that I had had for the last 5 years (IRH Elite), but unfortunately the manufacturer has changed the shape and it no longer fits me. I loved my old helmet and was quite disappointed! Fortunately, free returns with Smartpak!I tried this helmet as there are limited options in the larger helmet sized (and within my price range..), and I am happy I did! This helmet is well ventilated, great looking and the shape does fit my head. The stock helmet liner makes the helmet a bit too tight for me, but I verified with the manufacturer that I can get the next liner size up and that will give my head a bit more room. The chinstrap is a bit tighter than I was expecting, but honestly I think I have been keeping my chinstrap too loose!
    Date published: 2015-08-11
    Rated 5 out of 5 by from Excellent Product! I needed a new helmet, and after lengthy research of all products I decided on a One K Defender helmet. I heard others rave about the comfort in the helmet but did not believe how comfy a helmet could be until I tried mine on. The chin strap does fall in front but frankly it makes the helmet seem more secure. I got a wonderful buy through SmartPak's recent sale. I could not be happier.
    Date published: 2015-08-08
    Rated 5 out of 5 by from Cool and Comfortable I bought this helmet because I had heard the One K was light weight, comfortable and cool. It has proven to be all of these things. I can feel the air flow through the vents which helps keep my head cool on those hot summer days. It is a great price for a schooling helmet.
    Date published: 2015-06-06
    Rated 5 out of 5 by from Great helmet! I absolutely love this helmet and you can't beat the price. My Samshield never fit right but this one fits great. Usually wear a 6 7/8 and I have very long hair, the medium fits perfect.
    Date published: 2015-06-06
    Rated 4 out of 5 by from Nice helmet I really like the way this fits on the head, however, the chin strap is a little snug. I feel it on my chin which I am not used to. It has been a while since I used to ride, so I have not purchased apparel in a long time. I decided to keep it and just deal with the strap issue. I was a little disappointed that the chin strap does not have enough slack to fit appropriately given the price.
    Date published: 2015-06-02
    Rated 5 out of 5 by from Love this helmet! I decided to purchase this helmet after my old charles owen jr8 got too small. Originally I wanted to get another CO or a samshield, but that was until I tried on this helmet. It is by far the most comfortable helmet I've ever worn, has super ventilation that actually works, and is also super low profile even on smaller heads (no more egg head for me!!). The comfortable chin strap and removable liner are an added bonus as well. Could not be happier with this product and I don't think I'll be switching from one k anytime soon.
    Date published: 2015-05-05
    Rated 5 out of 5 by from Great helmet. Great price. I live in coastal South Carolina and it is HOT during the months of July, August & September. This is the first helmet I have had with good ventilation at a good price. It is also the most comfortable helmet I have had in years. I cut all of my hair off so had to get a smaller helmet. The One K Defender helmet has been fantastic. Really love it.
    Date published: 2015-04-28
    Rated 5 out of 5 by from Love! This helmet is comfortable, looks good, and is on the inexpensive side. It seems like an affordable version of a Samshield. I love the removable liner. I haven't been able to test it in the heat yet, but it feels nice and light while still being substantial enough to save my head. :D My favorite thing about it, though, is that it looks as nice as a $400 helmet for half the price!
    Date published: 2015-03-10
    Rated 5 out of 5 by from Great helmet at a great price! I needed a new helmet but I didn't want to pay $500 for one. I had tried on this helmet at a local tack shop and I loved it! I chose to buy my helmet through smartpak because they have wonderful customer service and a price that couldn't be beat! The helmet is a great fit though a little tight when my hair is up inside it. That's not a problem though because in due time I'm sure it will stretch just enough. I highly recommend this helmet for the rider on a budget!
    Date published: 2015-02-28
    Rated 4 out of 5 by from Nice schooling hat Great quality helmet, good shape and nice added ventilation. Sizing is accurate. The chin strap has a lot of added pieces on it which take some getting used to, but overall they are not bothersome.
    Date published: 2015-02-25
    Rated 5 out of 5 by from Great helmet I have had this helmet less than a month but have used it probably 20 times and I love it. It fits really well like it was made just for me, I didn't even have to adjust the straps! Very comfortable and well worth the price.
    Date published: 2015-02-17
    Rated 5 out of 5 by from Great fit I love my new helmet! It is very comfortable, stylish and easy to care for. I like that the liner is removable for more stinky helmets. Haven't used it in the heat of summer, but look forward to the improved airflow.
    Date published: 2015-01-30
    Rated 4 out of 5 by from great helmet! This helmet is super comfortable and the liner is awesome, it looks great AND at a reasonable price! The only con to it is the chin strap, and its only that it is a little stiff out of the box and sits a little bit forward on my chin, but other than that its super!
    Date published: 2015-01-26
    Rated 5 out of 5 by from Great helmet! I just purchased this helmet a few weeks ago, and I love it! Beautiful quality. It is very lightweight which I really like. It seems very durable but I haven't had it long so I can't say for sure. I have an especially large head so it was important for me to have a low-profile design, and this helmet really has that which I appreciate. This helmet definitely runs small, be sure to size up if you are in between sizes.
    Date published: 2014-12-24
    Rated 5 out of 5 by from So pleased with this helmet! I am so glad I made the decision to buy this helmet after much research. Nicely padded and comfortable.
    Date published: 2014-12-23
    Rated 4 out of 5 by from Brilliant for everyday riding, comfortable! I bought this after I tried the Charles Owen Ayr8, and I much prefer the feel of this helmet. I wanted something primarily for schooling that would still look fine for showing. This is a fantastic helmet for everyday riding and still has some style. The removable liner is simply perfect and so smart! I also love the ventilation as I can actually feel a breeze through them. For the fit, I definitely have an oval shape but this helmet fits very well. My one complaint is the chin strap as it is pretty bulky and rests pretty far forward. I have a petite face so the straps are a bit overwhelming. Overall, I am very happy with my decision when I picked out this helmet.
    Date published: 2014-11-24
    Rated 5 out of 5 by from In LOVE I purchased this helmet after I got a concussion in my old helmet. I liked the look of samsheilds but not the price so I decided to go with this helmet... and boy am I glad I did!! This helmet is goregeous! It fits like a glove! Did I mention the padding? Just Like a Pillow! I am so happy with this purchase!!
    Date published: 2014-11-05
    Rated 4 out of 5 by from Very Comfortable, makes wearing a helmet enjoyable Only have had it about a month and I am still in love. It slips right on and feels secure. The vents make riding in the heat much nicer, you can feel the air moving through the helmet! The only thing that could improve is possibly the chin strap. It is comfortable and I am more than use to it now but it is much different than the Charles Owen, which is what I'm used to. It's a great helmet for schooling and might even pass it off as a show helmet it is very classic.
    Date published: 2014-10-31
    Rated 4 out of 5 by from The only helmet that fit! My 5 years were up on my last helmet, and it was time to get a one. To my dismay, most of the helmets made today did not fit my large (~7.5") head. The sales girl at the Natick store was very patient. This was the closest to a good fit that I could find. No pressure points. The harness is a little uncomfortable as it is plastic, and tho the helmet itself just fits, the harness is too big and can't be tightened as much as I would like. But there was no better option. I am concerned that the harness may not last 5 years - but time will tell. For the price, I would have expected a leather harness.I can't believe that helmet manufacturers don't make anything larger than a 7 3/8 helmet!
    Date published: 2014-10-16
    Rated 5 out of 5 by from Great helmet for the money I purchased this helmet for my daughter when she suddenly needed a replacement due to a harness failure on another brand helmet. I knew the One-K would fit her head shape as she had tried one on belonging to another rider at our barn. This helmet is well designed and well made. While I was worried at first about the discrete sizing, the nature of the One-K liner and the material it's made from made for a perfect fit. I also like the velcro adjustment on the chance of the end of the strap blowing in the wind. Overall, I'm very impressed and would consider this helmet again for future purchases.
    Date published: 2014-09-25
    Rated 4 out of 5 by from comfortable and amazing look my daughter bought this helmet and it's super lightweight and comfortable! definitely easy on the wallet compared to other helmets like this, but still great quality. my daughter loves the look of it too!
    Date published: 2014-08-26
    Rated 5 out of 5 by from I have been wearing this helmet for 2 weeks now and I like the fit. The under chin strap I find a bit too forward but I tend to think that this is the correct place for it.
    Date published: 2014-08-11
    Rated 5 out of 5 by from Easy ordering great customers service quick ship Bought the 1k helmet & my daughter loves it. It's very hot were we live and this helmet let's her head breath
    Date published: 2014-08-05
    Rated 4 out of 5 by from Fits like a glove! Was hesitant on ordering a helmet online, but on sale and took a chance. Followed the fit guide and the helmet fits perfectly, no adjustments needed. Doesn't wobble, and so far in summer riding it keeps my head cool. Only issue I hope works itself out a bit are the chin straps - they're a bit stiff so maybe after some more wear they'll break in.
    Date published: 2014-08-05
    Rated 5 out of 5 by from Very Comfortable This is my second One K helmet. They are so comfortable that I decided to toss my old brand and have a spare!
    Date published: 2014-08-05
    Rated 5 out of 5 by from Beautiful helmet! This is a lovely, classy helmet. Whether you are an eventer, dressage rider, or H/J this helmet is flattering and professional looking. Love the fit too!
    Date published: 2014-08-04
    Rated 5 out of 5 by from Fabulous helmet! After several years in an IRH with a chinstrap that would slip occasionally, I decided to upgrade. I originally purchased an IRH Air but it looked too big on my head, so back it went (Thanks Smartpak for the easy return!). I exchanged it for the OneK Defender, and I am so glad I did. It looks great (low profile) and is so comfortable. I showed in it last weekend and in the hot weather, I could feel the air moving through the top of the helmet. Worth every penny.
    Date published: 2014-07-22
    Rated 5 out of 5 by from A- helmet, great price! I've had my CO ayr8 for longer than i should probably admit, and I have never found another brand that fit. It's pretty flattering and classy for the price and the vents seem like they'll work even better than the ayr8. My only complaint so far is that it's hard to get on when you're putting your hair up because the velcro that holds the front of the liner in slides back. I'm sure there's another trick to it, so overall great helmet for the price! I'm a 7 3/8 and I bought the xl, which fits ALMOST as well as my CO with my hair up and even better with it down. I might still be showing the the ayr8 because it's more classic, but these are great and gaining popularity pretty fast!
    Date published: 2014-07-15
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