Free your cranks. Allows you to run any one of the plentiful 104 BCD 4-bolt chainring options out there as well as to run a standard 4-bolt bashguard if desired. Lines up your single ring with the centre of your cassette for optimal chain line and shifting. Fits all current (at time of writing) SRAM GXP removable spider carbon or aluminium cranks. Machined in Canada from 6061-T6 aluminium for optimum low weight and durability. Weighs just 65 grams.