It worked great, until it didn't. The unit doesn't exactly "strap on" as the description says. Rather, there is a permanent clip on the seat stem and a little "slide-on" piece that allows you to remove the light easily (for changing the battery, I suppose.) But that's the weak link too: if you put the bike on a rack or lean it against a tree and accidentally brush against the light, there's a very good chance it will fall off. And, for me, it fell , the cover came off and the batteries spilled out. The 2nd time this happened to me, the unit died....so, maybe a month's use??