Petzl - Vertex Vent, Ventilated Helmet for Work at Height PROTECT YOUR HEAD: Shock absorption achieved through deformation of the outer shell. STAYS PUT: Strong chin strap (more than 50 daN) limits the risk of losing the helmet during a fall. COMFORT IS KEY: Features six-point textile suspension that conforms perfectly to the shape of the head. CenterFit adjustment system adjusts the headband and keeps the helmet centered on the head. BREATHE EASILY: Vent holes with sliding shutters allow the ventilation to be adjusted as needed, while wearing the helmet. PERFECT FIT: The VERTEX VENT comes with two sizes of headband foam.