S/M Bag that can be carried multiple ways. Over the shoulder with a detachable strap, around the waist or crossbody with the thick waistband that can be tucked away, or by the two handles. 7.3 Liter volume 13"w x 7"h x 4"d Padded main compartment large enough for a nalgene, book, plus more. Bright yellow inside to make finding things easier Two compression straps on bottom External bike light attachment loop Internal organizational pocket External zipper pocket with key clip, and two organizational pockets