All Wheels Manufacturing replacement derailleur hangers are produced in Colorado to exacting tolerances. - Dropout-374 is the direct mount version of dropout-284 - Replaces specialized part # S182600003 - For use with Shimano direct mount rear derailleurs - CNC machined 6061 aluminum - Black anodized finish - Attaches to frame with (1) M5x10 socket head screw (fastener not included)