Cannondale crankset sleeve for CAMO derailleurs only. There are several versions depending on the type of frame. M9 (minus 9 mm - standard converter towards the frame) For use on standard (non-Ai offset) bikes M4 (minus 4 mm - Ai offset) For use on Cannondale bikes with Ai offset rear triangle (asymmetric integration) And all Cannondale bikes 27.5 Plus For use on 2x Fat CAAD (166 mm spindle) Weight: M9 - 32g | M4 - 28g | M2 - 28g Material: 7075-T6 aluminum Made in USA