One K Helmets Size, Fit, and Style Guide

by Michelle Drum November 08, 2021 5 min read

Equestrians wearing One K helmets

Equestrians will tell you there is no more rewarding sport than horseback riding. And while that’s true for many, it is also one of the more dangerous sports. Horse riding may get less attention from a safety perspective than football and soccer, but there are numerous risks of riding horses, including the risk of head injury. Investing in a good quality helmet that meets or exceeds established safety standards is essential for keeping riders safe. One of the leaders in quality riding helmets is One K Helmets. In this guide, we’ll share what you need to know about their helmets and why we love them (and think you will, too!).

About One K Helmets

When you purchase a One K helmet, you’re choosing a company that’s invested in the perfect synergy between function, comfort, and fashion. This is a company that understands the unique needs for equestrian helmets and balances the need for safety with advanced technology, without compromising on rider comfort or quality. The result is an aesthetically-pleasing helmet that riders in all English riding disciplines will love, including dressage, hunters, jumpers, eventing, and equitation. 

One K helmets exceed safety standards in all tests, including impact, side distortion, and penetration. All helmets are made from the highest quality materials, including a polycarbonate and ABS composite injection-molded outer shell with an EPS liner for maximum impact absorption. They also have a number of comfort features that come standard with all One K helmets, including a moisture-wicking, anti-microbial, and washable liner with an adjustable comfort padded harness.  

These helmets don’t skimp on ventilation, featuring two front, two side, one back, and two center stripe vents for optimal airflow. On top of the already stylish design, they also offer some incredible customizations for personal flair. One K helmets have a fantastic and well-earned reputation, and they even earned a spot on our list of the top five safest horse-riding helmets. They may be one of the newer kids on the block when it comes to helmets, but they are also among the best.

One K Helmet Sizes

One K helmets come in multiple shell sizes and two shapes. They offer a regular and a long oval, the latter of which has a slightly narrower side-to-side measurement and an elongated head from front to back. Use the One K foam liners to provide any adjustments you need for the perfect fit. It’s still important to size your helmet properly, but this foam liner makes a great fit even better. And this system easily accommodates young riders and the adjustments they will need as they grow. Instead of buying a whole new helmet, they can simply change the liner size. Note that the regular and long oval helmets do use the same liners, as the shape is determined by the helmet shell and not the liner.

One K Helmet Sizing Chart

The sizing charts include measurements to select a helmet size and guidance for selecting the right liner size. The extra-small, small, and medium helmets can all be adjusted to different sizes. So the extra-small can actually fit extra-small, small, or medium, depending on the liner size selected. 

One K Helmet Size Chart

Top 5 Picks for One K Helmets

Here are our top-selling One K helmets, including some options for kids and some really fun customizations to add a more personalized touch. We’re sure you’ll find one to love in this list!

1. One K MIPS CCS Helmet ($325)

One K MIPS CSS Helmet

This One K MIPS helmet is a rock star! It integrates MIPS technology for added safety. It’s a great price for this advanced safety technology, and integrates seamlessly with an ABS polycarbonate shell. The liner is washable and moisture-wicking, as well as anti-microbial. If you’re looking for a stand-out helmet with the most advanced safety technology available, look no further!

Another fun feature of One K MIPS helmet is the color customization. With the custom color system, you can add your own personal flair. Add one of 13 colors to thefront shieldtop panel, or vent strip rail. You’ll stand out from the crowd for more than just your riding with this fun touch!

2. One K Defender Helmet ($269.95)

One K Defender Helmet

We love this helmet for its safety features and built-in amenities. This advanced ABS composite outer shell with an injection-molded shell design checks all the boxes for safety. And the padded harness with synthetic suede lining and seven vents ranks this helmet high for comfort. And don’t you worry — they didn’t skimp on style. It comes in a matte or glossy finish, stylish suede, or with rose gold accentsReplacement liners to refresh old ones or to resize your helmet are available.

Kids will also love this helmet, available in matte or suede.

3. One K Defender AIR Suede ($349.95)

One K Defender AIR Suede 

Another great option by One K is the Defender AIR. This helmet is fitted with an air pump system to provide the ultimate comfort and safety. Customize the fit until it’s perfect with an easy pump that fills three hidden air chambers in the liner. This helmet has an appealing suede finish, along with the standard safety, comfort, and convenience features. 

4. One K Defender AVANCE Wide Brim Helmet ($289.95)

One K Defender AVANCE Wide Brim Helmet - Black Matte

If you prefer a helmet with a wide brim, One K has got you covered! Enjoy all of the incredible features of the One K Defender Helmet with a nice, wide brim to protect your eyes from the sun. You can’t go wrong with this great helmet.

5. One K Skull Cap ($269.96)

One K Skull Cap

Calling all eventers — this helmet is the ultimate option for you! It features a textured shell, offering a great grip for a helmet with silk covers and all of the incredible safety and comfort features of One K helmets. These include an advanced ABS composite outer shell with injection-molded design, a quick-dry, moisture-wicking, anti-microbial, and washable liner, comfort padded harness, incredible ventilation, and so much more. 

Safety Meets Style

With a One K helmet, you can count on the advanced features to keep you safe and comfortable in the saddle. Plus, these helmets are made to impress, and you’ll get high scores for the design. If you’re looking for a great line of helmets, One K is the brand to beat!


Have questions about any of our breeches, pants, or tights? Give us a call at 864-457-3557. We’re happy to help. Our shop’s team is made up of experienced English riders who have a thorough understanding of the products we carry.


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