The Fuel Tank is part of Topeak s Top Tube bag range and features a large 0.75 or 0.5 litre capacity, easily enough to swallow a good handful of energy gels and bars, a smartphone, wallet, inner tube, tools and pretty much anything bar the kitchen sink! The zipper accessed top allows easy access and the divided main compartment and inner mesh pockets keep things neat and tidy, while also helping keep the possibility of a smartphone covered in energy gel to a minimum! The 0.5 Litre version also features a battery access port for charging a mobile phone.1800 Denier Nylon/PVC SpongeNylon StrapsMedium : One main compartment with one inner mesh pocketLarge : Divided main compartment and two inner mesh pocketsCable access hole for charging devices via mobile power packMedium: 17.5x7.5x11cm, 0.5L, 120gLarge: 24x7.5x11cm, 0.75L, 120g