Ultra lightweight Grade5 Titanium Starter Nuts to use with external starters with 5/16" hex (Coleman, Burris, etc.), 1" Length x 5/8" Diameter. Fits X30, Leopard, PRD Fireball, Rotax, HPV, KPV, Rok GP or any engine that uses a 10x1.0mm threaded crank nut. Check rules for legality!