Giro Source Mips Helmet - Matte Sky Blue Pulse Size:L 5 mm outside spline diameter

5 mm outside spline diameter used in FORE™-drilled rims:

Material: Aluminum / Engineering grade polymer

SystemSix and Synapse

5" ICR headsets such as the Acros ARCRise: 20mmSize: 780mm wide

If you arrived here looking for the ER:ONE

Giro Source Mips Helmet - Matte Sky Blue Pulse Size:L 5 mm outside spline diameterThe Source Mips helmet combines advanced performance and protection in a rugged, trail ready design. Featuring deep coverage with aggressive ventilation from 17 vents coupled with deep internal channeling, it helps keep things cool even when the riding gets rowdy. And with the comfort and secure feel of the Roc Loc 5 Mips fit system with Integrated Mips brain protection, plus a moto style adjustable screw in visor and full lower Hardbody durability,