The Grivel Mutant is built for climbers who move between the crag and the mountains and want one helmet that handles both without adding noticeable weight to the pack. EPP foam and ABS reinforcement work together across the full use cycle: the foam absorbs repeated low-level impacts on busy cragging days, and the ABS shell at the top handles the sharper, concentrated force of rockfall. The stripped-down adjustment system keeps the profile compact enough to compress into a pack on the approach, and three sizes cover a wide range of head shapes without relying on a bulky dial mechanism to compensate. What Our Gearhead(R) Experts Are Saying:"The EPP foam holds up to repeated knocks without degrading the way EPS does, so this helmet stays in rotation for years of regular cragging and alpine days rather than needing replacement after a single significant impact."