The Hope E-Bike Spiderless Retainer Ring Boost is designed specifically for E-Bikes and uses a narrow/wide design to grip onto the chain and stop it from dismounting when riding over harsh and uneven terrain, which theoretically means you can ditch your chain guide for this simple and clean looking system. They are constructed from CNC machined 7075-T6 aluminium that provides the perfect blend of strength and being lightweight, a hard anodised finish make them ultra durable and increases longevity.Hope E-Bike Spiderless Retainer Chainring Highlights-Direct mount retainer ring designed specifically for Bosch, Brose & Shimano Motor E-BikesSaves weight without need for a separate spiderThe narrow/wide chainring is designed to retain the chain without the need of a chain deviceQuieter drivetrain and less dragCNC machined 7075-T6 aluminium provides the perfect blend of lightweight and strengthCompatible with 9, 10, 11 and 12 speed set-upsHard anodised finish makes them ultra durable and increases longevity34T