• The Universal Derailleur Hanger (UDH) consolidates thousands of mountain bike derailleur standards
• Provides unparalleled derailleur protection, and perfect alignment. Guaranteed.
• Designed to rotate rearward in the event of impact and features the ability to "re-rail" the chain back onto the small cog
• Works with all commercially available MTB and E-MTB drivetrains from Shimano to Box to Sunrace

(H/T XKCD, and yes there are currently 224 Derailleur Hangers on Wheels MFG right now)