Prima Roller Weight Set - 20 x 17 mm (Vespa), setRoller 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 youre a heavy person (and or) if you have a stock motor you will want to lean towards the lighter rollers. If you are a