Featuresr 20l capacity cycling backpack with a 2 liter water bagr special hole design for water bag and two clips on each strap to hook water piper made of ultralight water resistant and tear resistant nylon fabricr uses high quality sbs brand zipper with pull ring rope for convenient user mesh and thickening poriferous eva design on the back for maximum breathability and comfortr adjustable shoulder strap chest strap and waist strap to fit your need and a built in whistle on chest strap