Free Pack provides an alternative way to pack most inner tubes with a mini tool or CO2 cartridges for your ride. Mounts to saddle rail with included Duo Fixer which 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. UPPER MOUNTING OPTIONS Fenders / Repair Tools / Tail Lights LOAD UP WITH GEAR OPTIONAL Inner tube up to 29” x 2.6” / Mini tool or CO2 cartridge*Max gear load 450g / 15.9oz SADDLE COMPATIBILITY Compatible with steel CroMo titanium and carbon standard saddle rails with 36mm width spacing and at least 30mm height spacing. Not compatible with monorail or spring type saddle rails MATERIAL Engineering grade polymer ATTACHMENT Duo Fixer on saddle rail COMPATIBILITY Upper: TubiMaster GX DF NanoMaster DF TailLux DF lights and FlashFender DF with upper bracket SIZE 10.4 x 6.7 x 1.8 cm / 4.1” x 2.6” x 0.7” WEIGHT 45 g / 1.59 oz ADDED FEATURE 3 mounting straps 2 tire levers included