Topeak DF Duo Fixer Mount – Saddle Rail Accessory Mount. A saddle rail fixer that allows fast and easy tool-free mounting and removal of two separate accessories that are QuickClick equipped underneath the saddle cleanly and securely. Duo Fixer system allows to mount Topeak QuickClick saddle bags or most strap type saddle bags and provides dual use with Topeak Duo Fixer system accessories including Tubi tools CO2 inflators lights and fenders. A simple slide and click is all it takes to go on a safe and secure ride.