SR Rolls from the PRO SERIES line by Dr. Puleggia broadens your spectrum by moving upper and lower due to their particular shape. Now, it is possible to improve acceleration values ​​and achieve higher top speed, all with a single set of specially formed rollers. Which means you can avoid having to buy two different types of round buns to do each job separately. These two in one rolls are incredibly popular in the US scooter scene as well as Asian scooter scenes in Hong Kong, Taiwan and Japan. Attention: The weight of standard rolls used up to now cannot be converted from 1: 1 to SR rolls. An accurate calibration of +/- 1.0 grams is required. It is also advisable to adjust the vario springs. If too heavy rolls are chosen, it will be great for top speed, but the fan belt can rub on the motor body. This is why it is recommended to calibrate exactly. SIP-Tipp: You will have better results using roller weights with the DR. Pulley chute pieces!