The aluminum sliding pieces of the Tange/IRD Sliding Dropout. Also fits IRD Broski Dropouts Left side has an IS disc tab. Right side has a derailleur hanger. For QR hubs. Your best option if you bent or cracked your derailleur hanger on a Soma Juice, Riff, Wolverine, Ritchey P-29 or Citizen. Bolts not included.