This is a hydraption pack,which can use for outdoor sports,like running,cycling,hiking,camping,climbing and daily training. 1.The fabric is nylon ripstop with PU coating 2.Size is L20*W6*H42cm 3.screen printing and reflective band on the front part for visibility and safety 4.front pocket with #5 zipper for keys, phone, snacks etc 5.external expandable stash zone with 2pcs durable buckles for towel,clothes etc 6.main pockets with #5 zipper,you can put 1.0~2.0L bladder by plastic hook inside 7.mesh shoulder padding and back for breathable, 8.two sides can be used suitable for both left and right handers 9.special zipper puller 10.elastic strap on the shoulder strap to hold the pipe. 11. wrist straps with buckles can stop shaking 12.inside silk binding to be strong 13.handle straps for easy carry