The back is made of mesh material. It has two front bottle pockets. Product number: NM61813 Capacity: 15 liters Used only a few times for short walks, it is in a clean condition with no stains or scratches. Please refrain from purchasing if you are sensitive to used items. From an online sales site: This is the latest large model in the Martin Wing series, which is highly popular as a running pack for races. Seeking further convenience, the fit, breathability, pocket placement, and capacity have been updated. It has pockets on the front that can hold 500ml bottles. The hip pockets have also been increased in capacity, and a storage pocket that is easily accessible even while moving has been added to the lower part of the main body. The main compartment uses a J-shaped triple zipper, allowing side access. With a simple design that eliminates waste, it is easy to use not only for races but also for everyday road runs. ■Function ・Air mesh back for excellent breathability ・Reservoir-dedicated compartment (2L compatible) ・Main compartment that opens wide with a J-shaped zipper, also supports side access ・Mesh pocket with key clip in the front pocket ・Side compression ・Bottle pocket with drawcord on the shoulder ・Hip pocket with slit pocket ・Large storage pocket at the bottom of the main body ・Non-slip tape on the back of the hip belt ・Reflector ・Lash point for bungee cord ・Bungee cord and cord locker included ■Country of origin: Vietnam ■Size: L ■Weight: L/approx. 440g ■Dimensions: L/H50 x W29 x D9.5cm