On The Ball Bowling (OTB) is now officially licensed by MOTIV to create a designer series of polyester spare balls. The MOTIV design team works closely with OTB to create every ball in the line.Specs:- Cover: Polyester- Surface: poliert- printed cover- Core: Pancake- R.G.: 2.62- Diff.: 0.020- Weights: 6, 8, 10, 12, 14, 15, 16 lbs