This idea started years ago when cyclists started hacking the tops off their water bottles to turn them into storage containers. Why? They wanted to store their stuff at a lower center of gravity than where a saddle bag was. More than enough space for a road tube, patch kit, and pocket tool. Small size: 5.5" tall, Large : 7.5". Fits snugly in most water bottle cages. - Silver color keeps interior cooler than black bottles Minimal graphics may attract fewer thieves than bold graphics.