Product details:

Renthal Twinring Heavy Duty Rear Sprocket - 48T (Aluminum) - Unique flat face design keeps weight to a minimum and means the TwinRing is as narrow as a regular chainwheel. Inner Ring is high strength Ultralight 7075 T6 Aluminum. Outer Ring is Electroless Nickel Coated steel. Outer is expanded at 200C and then fitted to inner, creating a permanent bond for the life of the sprocket. Precision CNC machined to extremely tight tolerances. Flat socket head screws add additional strength to the chainwheel during side impacts. Self-cleaning mud grooves between every tooth on both sides help prevent dirt build up.