Fortified Bicycle Lightweight Aluminum Afterburner Rear LED Light (30 Lumen) Never take your lights off again: Custom security bolts guarantee your light against theft Never ride uncharged: Custom removable USB rechargeable li-ion batteries enable quick swapping on the go See the road: 30 lumen rear light make sure traffic sees you and that you see the road Fits seat posts 22mm-31.6mm Ride bright for hours: Up to 24 hours run time