The moon arcturus auto pro rear light is an attractive light that will fend off any rear approaching vehicles or other cyclists the arcturus offers fantastic output from a small and lightweight chassis with 7 modes you are able to cycle through them all until you find the one that best suits the conditions you are riding in or the remaining battery life busting out a whopping 100 lumens this is bright for a rear light combined with an integrated light sensor the arcturus is ideal for the d