Stainless steel. Adapter 1/2-20 male (crankcase side) to 1/8″ NPT female (oil gauge side). Used between crankcase and oil gauge fitting. Excludes the required 507195 (OEM 11105) O-ring. Note: See optional 901220 (chrome) or 900879 (stainless) 45? adapter fitting to give the rider a better view on the oil gauge; while riding.