The ORB Bar End safety lights pair a sleek, compact design housed in an alloy chassis. Conveniently, the lens itself serves as the light`s operating switch and is protected from inadvertent triggers due to the housing`s design while still allowing for side visibility. Fits neatly into road bike handlebars that have a inner diameter of 18.5mm-22mm and improves your chances of being seen, both from the rear and side. Runs off 4 CR2032 batteries (included).