Large capacity top tube bag with an easy-to-use Velcro mounting system. Convenient top tube mount keeps contents close at hand. Perfect for storing a mobile phone, energy bars, a wallet or tools. Made of 1800 Denier Nylon/PVC SpongeNylon Straps. The medium size has one main compartment with one inner mesh pocket, while the large size has a divided main compartment and two inner mesh pockets. It also features a cable access hole for charging devices with a mobile power pack. The medium size measures 17.5x7.5x11cm and weighs 120g, while the large size measures 24x7.5x11cm and weighs 120g. Please note that sand, dirt, mud, etc., and bags that are incorrectly packed may cause the bike frame paint in contact areas to become dull or scratched over time. To avoid any potential damage, you should protect the frame or rack with foam covering or protective film before attaching bags or panniers.