Bell M8 Ultra Helmet 12100908 and the bore size is

and the bore size is prominently engraved in 3/4 in high numbers for easy identification

Silver Aluminum Caps To Match Your Engine Bay

1971-1974 Chevrolet Bel Air

1994-1996 GMC C1500

1/16 in NPT Right Hand Thread

Bell M8 Ultra Helmet 12100908 and the bore size isDesigned for closed cockpit forms of racing, the M8 Ultra is the next evolution in Bells legendary M series design platform. The M8 Ultra incorporates traditional styling, enhanced visibility, with maximum versatility allowing the helmet to be used in all forms of racing. With a lightweight carbon shell, premium interior, superior ventilation, and large eyeport for racers who require eyewear or prefer maximum visibility, the M8 Ultra provides next