The Enduro/XC system prevents the chain from hitting the rear structure - the result is a completely silent ride on any terrain. One 3D printer, a bunch of CAD and prototypes, 2 seasons in whistler bike park and this is the final result. The ultimate feature that stops the chain from knocking and turns your bike into a silent bicycle. Suitable for trail bikes with 1X gears (one derailleur) 9-13 speeds with cassette up to 52 teeth Dual compound design for optimum stiffness, durability and noise damping Adjustable length to fit most bikes Light weight and quiet operation Please check compatibility before purchase