Ok lots of question....The overdrive has a combined weight limit of 20K,I just havent tried any more than this yet.It is a single overdrive only.Ive sold several on ebay and everyone likes the quality and the price$1500-1600.ive been working on this stuff for two years.im on a limited budget.The only BIG snag so far is the owner or GEAR VENDORS is mad as hell, that i can make them so cheap and just like there units.I also have an electronics package that works great and is cheap by comparison $150.00.GV doesnt like what im doing at all.