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.
This product can expose you to chemicals known to the State of California known to cause Cancer or birth defects and reproductive harm. For more information go to: https://oehha.ca.gov/proposition-65