Petzl A11 R1 Vertex Vent Helmet, Red Ansi c ertified: z89;1 type 1 class c Complete adjustabilty for a custom fit-single adjustment wheel to adjust headband size Standard side slots for mounting eye and/or ear protection (peltor, bilsom, 3m, etc;) Over-the-ear shell design allows hearing protection to fi t properly Chin strap adjusts forwards or backwards