Drop outs (derailleur hangers) are a sacrificial component of your bike, designed to bend or break in the event of an accident - saving your frame from being damaged. Always have a spare, as the bike is un-rideable without one. Cast Aluminum Comes with 2 mounting bolts included. Fits: Bike Model Type Year Helios A4 A5 -A6 A7 A8 A8X A9 A9X 2013