Specifications: Sepcifications for these high performance parts/tuinging parts/racing parts: Item number: C-1 Specifications: As high performance parts, this is a hi-performance race 2-shoe clutch with fully adjustable! Hi-performance race springs Fully adjustable Better clutch engagement European race quality Easy to install Easy to adjust Light and built to last Used only the 47cc/49cc mini-pocket bikes. Item number: C-2 Specifications: Suitable for water-cooled engine Item number: C-3 Specifications: This clutch can be for 49 cc air cooled engine, for all scooter bike. Item number: C-4 Specifications: This clutch can be for aircooled engine, for all scooter bike. Other performance parts/tuning parts/racing parts are also available for scooters, mini-motos, pocket bikes, dirt bikes and atvs. For example: 1) different types of exhaust pipes/mufflers 2) different types of clutches for both 2-stroke and 4-stroke engine, air-cooled and water-cooled, clutch springs 3) cylinder, pistons, rings, pull starter, and gearbox,4) carburetor, air filter, stacks, intake manifold, gasket, jets for both water-cooled and air-cooled 5)brake caliper, brake level, throttle lever, chain, sprocket, foot-pegs, front fork etc.