PRO 1:Saving time wherever possible is important to a triathlete and the Tri-BackUp Pro I aids by mounting to the parallel section of your saddle to form a rear saddle hook helping to minimize T1 and T2 times. This sturdy rack also provides multi-combo capabilities to customize equipment for any race needs. MOUNT Parallel rail section of saddle Compatible with CrMo Ti and Carbon rails MATERIAL Pressed aluminum HYDRATION CAPACITY One or two bottles up to 750cc each MAX LOAD 2.5 kg / 5.5 lb COMPATIBILITY Tri-BackUp Air Station Tri-BackUp TubeBag Tri-BackUp TireBag Ninja TC Road Ninja Pouch+ Road. Ninja CO2+ Tri-Cage ADDED FEATURE 2 angle positions SIZE 12.5 x 8 x 4.8 cm / 4.9” x 3.1” x 1.9” WEIGHT 97 g / 3.42 oz PRO V:Saving time wherever possible is important to a triathlete and the Tri-Backup Pro V aids by mounting to the “V” section of your saddle to form a rear saddle hook helping to minimize T1 and T2 times. This sturdy rack also provides multi-combo capabilities to customize equipment for any race needs. MATERIAL Pressed aluminum MOUNT V rail section of saddle Compatible with CrMo Ti and Carbon rails HYDRATION CAPACITY One or two bottles up to 750cc each MAX LOAD 2.5 kg / 5.5 lb COMPATIBILITY Tri-BackUp Air Station Tri-BackUp TubeBag Tri-BackUp TireBag Ninja TC Road Ninja Pouch+ Road. Ninja CO2+ Tri-Cage ADDED FEATURE 2 angle positions SIZE 11.8 x 8 x 6.9 cm / 4.6” x 3.1” x 2.7” WEIGHT 97 g / 3.42 oz