Cold forged, high grade hardened steel designed specifically for E-Bikes and longer wear- Silver version with PVD coating lowers friction and makes it longer lasting and super durable- These e-rings are female-threaded. Use a M8 bolt to thread directly into this threaded e-ring for motor clearance. Mount with the logos facing outward. Bolts not included- Narrow Wide tooth profile for better chain retention- Works with 1x10/11/12sp Shimano, KMC and SRAM Eagle, Flat and T-type chains- Must use a 'clutch' type rear derailleur. Ex: Shimano Shadow or SRAM Type2- Shimano compatible with both mechanical and Di2 Shimano 10/11/12sp. SRAM compatible with both mechanical and wireless SRAM 10/11/12sp- In rough terrain, or just for pure security, use of an upper guide recommended