The Mag-Tank takes a new twist on top tube bags. Instead of a zippered opening, access to the bag is by contoured top flap held in place by a magnetic buckle with mechanical engagement. It will not unintentionally open and spill your gear. One-hand access while riding Side panels stiffened with HDPE plastic sheets Wrap around panel design is padded with closed cell foam Adjustable height daisy chain front attachment with foam spacer block Please note - while the cover to this bag is designed to shed rain and spray, due to the large panel opening it is not a sealed bag or water-proof Length: 8.5" Max Height: 5" Width at stem: 2.5" and tapers to 2.5" tall and 1.5" along top tube 55 Cu in