Piston 63mm GY6 150CC FORGED ( high compression piston kits will deliver peak performance in all applications due to our extreme precision machining process. These pistons are able to provide a stronger more durable piston at a lighter weight allowing for faster revving and more horse power throughout all power ranges. Machined from 2618 T6 high tensile forged aluminum Dome/Dish features smooth flowing radii and require no deburring or preparation MRP FORGED Pistons are specifically engineered for extreme applications including professional competition Pression ring lands and engineered over size oil passages ensure peak performance and durability MRP forged pistons will out perform any stock piston every time. RINGS MADE IN JAPAN FORGED PISTON MADE IN THE USA Dia at skirt; 62.91mm Dia at top to 1st ring: 62.51mm Pin; 15.01mm Pin hole to top of piston; 12.66mm This is for scooters with 150cc and 125cc GY6 QMI152/157 QMJ152/157 4-stroke engines. This is the most popular 150cc automatic engine found in 150cc and 125cc Chinese and Asian made 4-stroke scooters.