S: 21-28mm internal rim width

Lockring interface: 8 notches

This is the youth model so it's perfect for grom sized heads

get some TL-6

Depending on who's review you read these can also be a bit of a battle

POC Joint VPD Air Knee Pads - L - Basalt Blue PLP|Largest Cog S: 21-28mm internal rim widthLightweight and flexible padding that is barely noticeable ideal for riders who want complete freedom of movement and reliable protection. The VPD Air padding is both highly flexible and highly ventilated for optimal freedom of movement, comfort and temperature control. The pad is housed in reinforced stretch fabric that stays securely in place thanks to an inner lining of anti slip neoprene and an elastic strap with velcro fastening. A low profile