Back Spin : 12 Speed : 7 Control : 9 Thickness : 1.80±0.03mm Colors : Black Pimple Out : Long Pimple Sponge Colors : Red Sponge Thickness : 0.5 mm 1615 Moster Rubber is one of the series of 1615 long pimple rubbers, and features cunning long pimples. The rubber is thin but well-proportioned. The thin and flexible pimples will reshape irregularly when hitting, which can create counterforce to make the ball to move swiftly and uncertainly. Also the unique pattern on top of the pimples can increase the friction and back spin force.