This Stage6 Boost Bottle is especially designed for 70cc engines. Like the Doppler version, it has a solid chamber, which prevents the airstream from oscillating back and forth through the carb's venturi when throttle is lowered, hence the airstream is only charged with fuel once which improves pick-up when throttle is opened. This way your scooter also will have less problems with an overly rich mixture and it adds up to lower fuel consumption and better throttle response. Highly recommendable with a big bore carb, which often can have problems with a rich mixture at lower revs. Comes with all the small parts needed for fitting.