They are either a 6

Non-Porous - will not harden

Only because you asked so nicely

Compatibility: All Bell Super 3R and the Super 3 Models

and TRP brakes are not supported

Bell Sidetrack 2 MIPS Helmet - Youth - One Size Fits Most - Matte Black - AS-NZS�2063-2008 Standard Dropship They are either a 6The Bell Sidetrack 2 MIPS offers all around coverage, an easily adjustable fit system, and an adjustable visor making it a great option for young riders. 14 vents help to keep their head cool and sweat guide padding helps to keep the sweat out of their eyes. The helmet features a MIPS liner to provide extra protection for the brain from the effects of rotational impacts and the sharp styling should make for fewer complaints when it's time to put it