Latest variator technology from Polini for untuned 50cc engines for improved acceleration and higher top speed. Polini evo sliders make for better power transfer and shifting.No additional tuning required, so a great option for untuned scooters. Delivery contains: Hi-Speed variator with sleeve, 2x counter pressure springs, Evo-sliders, 2x sets of variator weights (19x15.5) at 6.3g and 5.g, and a Polini drive belt.