Dr. Pulley High Performance HiT Clutch Kit for 50cc 4-Stroke 139QMB ScootersSPECIFICATIONS:Inner Diameter (bell): 107mmOverall Height (bell): 34mmNumber of Splines (clutch bell): 2260 Degree Pillow SpringsIncludes Assortment of Pillow Springs and Clutch Springs for fine tuningDr. Pulley HiT Clutch 161301 with Bell for Scooters with 50cc/90cc/100cc Honda, Piaggio, PGO, Kymco, SYM or QMB139 engines and four-wheelers with 50cc/70cc/90cc/110cc Kymco, SYM, Honda, Piaggio or QMB139 engines. This clutch assembly is recommended for ATVs, Buggys and GoKarts or Scooters with modified cylinders.**