Scooter Roller Weight Set, Prima – 15 x 12 mm (Yamaha, Minarelli) – 5.5g / Sc… This will fit ALL Yamaha based 50cc horizontal 2 stroke engine with 15X12 size rollers Roller weights are used for fine tuning your scooter to get the most out of what you need from your scooter. Tuning Tips: Light rollers are good for quick acceleration, stop and go riding and hills, but you loose top end speed. Heavy rollers will give you a higher top end speed (long roads) but you will loose low end acceleration. If you’re a heavy person (and/or) if you have a stock motor you will want to lean towards the lighter rollers. If you are a light person (under 140lbs) or you have a big bore you will want heavier rollers Fast order processing! Important Parts Notice: Not all parts come with instructions. It is the customer’s responsibility to properly install or hire an experienced installer. We are not responsible for any damage that can be caused by improper installation. Electrical p