Adjustable Maritime ABS Tactics Helmet /DE Large to X-Large Adjustment Rear Dial Knob for Head Size adjustment. Available MED/LG 22" - 24" (57CM - 61CM ) Side Rails w/ Goggle Strap Clips & NVG Shroud, Bungee Retention for NVG Material: ABS! Not Designed to Withstand or Protect Against Real Ammunition.for CS Game Bike! Velcro Panels Allow Fitment of Patches. Please measure your head before make an order