"We have sold 19 of these in the last 6 months"

Roller weights, also known as variator rollers, are components used in the automatic transmission system of motorcycles, particularly those with a continuously variable transmission (CVT). They are cylindrical weights housed within the variator or clutch assembly. As the engine speeds up, the roller weights move outward due to centrifugal force, causing the variator to change the gear ratio and adjust the transmission. This allows for smooth acceleration and efficient power delivery.