SHIMANO SM-BTC1 Battery Case for SM-BTR2 Cap-C Nut M3 and Cusuion-C - Y7GB98020 Cap-C Nut & Cushion-C - M3 (Y7GB98020) compatible with (SM-BTC1) Battery Case for SM-BTR2 Original Shimano parts guarantee that all components work perfectly for optimum performance and maximum safety and longevity.