I use it to hold a Specialized range extender battery for my Turbo Creo SL. I tried a normal bottle cage but on washboard trails it will jump out because the battery weight around 5lbs. The two straps that come with this cage have one side rubberized (facing the bottle) and cinch down tight enough so that there is no way that expensive battery is escaping down the road. Yes, it's heavy and ugly and no, it's not aerodynamic but it serves its purpose.