Stock rollers for Rattler 50 are 11.5g, and stock for Black Cat, RoughHouse, and Buddy 50 are 7.5-8.5g. Try some different weights and make it scream!
Roller weights are used for fine tuning your scooter to get the most out of what you need from your scooter.
Light rollers are good for quick acceleration, stop and go riding and hills, but you lose top end speed. Heavy rollers will give you a higher top end speed (long roads) but you will lose 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.