Glixal ATKS-04012 16X13mm High Performance Racing Variator Roller Weights Set 139QMB GY6 50cc - 100cc Scooter Moped ATV (7 gram) Size: 16x13mm Weight:7g 6pcs/Set Material: High wear-resistant nylon Heavier roller weights= A slower take off speed and a higher top speed. Lighter roller weights = A faster take off speed and lower top speed. Please Note: The exact performance of upgrade parts will be affected by many other factors