This rectifier is made to work in conjunction with the 3600/H4 10.0 & ULTRA LED headlight module in machines that have AC powered headlights. One rectifier per bulb is required. This rectifier will also work for AC powered bikes using our Penetrator LED Headlights.
Most factory street legal bikes are DC powered, so this is not necessary for factory street legal bikes, exceptions being the KTM EXC 250/450/525/530 02-2011 carbed bikes, Yamaha WR450 carburetor version, and Honda CRFX 250/450. If you have a street legal bike from the factory that is not listed as an exception, you should not need the rectifier.