- 4-arm chainring for E-bikes, with a bolt circle diameter of 104mm, designed for hub gears. - Compatible with Bosch systems (Generation 3 and Generation 4) when used with Spider BCR-71E or BCR-72E. - Works with all 1 to 8-speed chains. - Suitable for hub gear systems. - Made from hardened steel for extended durability. - Chainring screws are not included (BCR-60).