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Arai XD4 Helmet.

Arai XD4 Helmet Features

  • New comfort headliner, with micro fitting 5mm peel away temple pads
  • Fully removable/replaceable/washable Interior: Comfort head liner, Cheek pads, Chinstrap covers
  • ry-Cool® technology keeps you dry and cool for greater comfort
  • Patent pending, New FCS® (Facial Contour Support) cheek pad design, also with a 5mm peel away micro fit feature
  • New shell shape for better aerodynamic stability at higher street speeds
  • New exhaust ports added to the top diffuser vents
  • New chin vent with more intake ports
  • Larger sculpted side cowl vents improve ventilation
  • DOT and Snell M2010 approved

Arai XD4 Helmet Sizing

To find the Correct size helmet for a person's head:

  1. Measure the head circumference one-inch above the eyebrows and ears
  2. Using the circumference measured, use the size chart below to find the approximate size
  3. Once you have tried on the helmet it should fell snug equally around the head. The helmet should not feel too tight or too loose at any point around head.

***Please remember that all head shapes vary slightly and that this sizing chart is to be used as a starting guide, not an exact guide.

Size Chart

Size CM Inches


49-50 cm 19-1/4"-19-5/8"
2XS 51-52 cm 20-1/8"-20-1/2"
XS 53-54 cm 20-7/8"-21-1/4"
SM 55-56 cm 21-5/8"-22"
MD 57-58 cm 22-1/2"-227/8"
LG 59-60 cm 231/4"-23-5/8"
XL 61-62 cm 24"-243/8"
2XL 63-64 cm 24-3/4"-251/4"
3XL 65-66 cm 25-5/8"-26"

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This XD4 helmet is an ultra-premium dual sport helmet offering from Arai. This is the pinnacle, the standard by which all other dual sport helmets are judged. Arai Helmets has always focused the majority of their efforts on safety, from the materials, to the shape, and other design elements. The DOT and SNELL rated shell is made of three layers. There is a shock absorbing pad layer that is sandwiched between layers of Arai’s proprietary Super Fiber and aerospace grade fiberglass. The goal is a shell material that is ultra-rigid. This rigid material allows the helmet to deflect off of objects with a minimal amount of deformation. Arai believes whole heartedly that reducing the amount a helmet shell deforms in an impact, keeps the helmet from catching on obstacles like curbs or uneven concrete. This reduces injury to the neck, spine, and clavicles, while the helmets advanced EPS system handles the impact energy. Notice the XD4’s shell shape. Even with its slightly elongated off road profile, the helmet is still as close to perfectly round as possible. There are no sharp edges to catch on anything, keeping with Arai’s theory. All of the vent covers and other extrusions will pop off easily in a crash. This is an intentional effort, again to keep the shell as round as possible when it matters. While other helmet companies have recently upgraded their visor hardware to metal, Arai believes that nylon screws are a better choice, to allow the visor to break easily away from the helmet. No materials on an Arai are chosen because they are less expensive. Every material chosen, every design implemented is for the purpose of added safety. The Arai XD4 is available in a large selection of colors and graphics, including this new Diamante graphic. To see the colors and graphics in greater detail, check out the high res photos at The shape of the helmet is intermediate oval, and it’s available in sizes extra small to double extra-large. The size chart on the listing is very accurate, so my 23 ½” head fits perfectly in a large as the chart recommends. While we’re talking about fit, we might as we take a closer look at the liner. The cheek pads and head liner are both equipped with five millimeters of peel away padding to help you dial in the fit. The cheek pads also feature Arai’s FCS or Facial Contour System. This design creates a snug and precise fit, but allows the helmet to be more easily put on and taken off. The cheek pads also have a built in safety feature in this emergency release tab. Pulling out on this tab allows the cheek pad to be removed before the helmet is taken off of the rider’s head. This minimizes movement of the head and neck when the helmet is removed. With the headliner removed, you can see the five millimeters of peel away padding in the temple area. Next, let’s take a closer look at the face shield and visor configuration. This is typically the biggest draw to this style of helmet. You have the combined features of a sun visor like those found on offroad helmets and a shatterproof polycarbonate face shield like those found on street helmets. Most of the helmets in this dual sport category allow you to use one or the other of these features or both depending on your needs. What sets one helmet apart from the rest is how these features interact with each other. While the setup on this XD4 looks very basic, there is actually a lot going on here. The Achilles heel for many of the helmets in this dual sport category is aerodynamics. The popular visor feature is stable at offroad speeds. But, at highway speeds, it can become a rudder of sorts, causing hard buffeting and oscillation. The trick is to keep the visor as close to the shell as possible. This can be a challenge because the faceshield needs to fit underneath the visor when in the raised position. Removing the visor exposes Arai’s solution. This is the Twin-Cam Shield Pivot System. This design draws the shield in close to the helmet when raised, and keeps the shield from protruding out past the peak of the visor. To use the face shield without the visor installed, simply install these included side plates to retain the shield. I found that installing either the visor or side plates is easiest to do with the shield in the closed position. With these plates installed, you get a good look at the functionality of the pivot system. This helmet can also be worn with the visor only, by simply removing the shield and reinstalling the visor. Even though goggles can be worn with the face shield installed, removing the faceshield will prolong its life when riding in very dusty or muddy conditions. These Max Vision face shields are available in a few different styles, with light smoke, dark smoke, and a Pinlock ready clear version available as well. Now, let’s take a look at this improved vent scheme. Arai is known for incredible ventilation with minimal reduction of shell integrity. This XD4 is a fine example. The new larger chin vent flows a ton of air to the face, and is flanked on either side by these two additional intakes. These vents are infinitely adjustable with these sliders inside the chinbar. There are also two eyebrow vents built into the faceshield that the XD3 didn’t have, and two additional vents on the top of the shell. Exhaust has been significantly improved over previous models, with four vent holes in these diffusers over the previous model’s two. The design of these new diffusers is very clever. The covers can be removed for easy cleaning or replacement. With the vent control in the middle position, you can slide this little red switch to either side and pull down on the vent control, releasing the cover. You can reinstall the cover with the switches in any position; just make sure you return the little red switch to the middle position to lock the release mechanism. If we look near the bottom of the shell, we can see the larger side cowl vents that work with the new chin vents to pull massive amounts of air through the helmet.