I believe @wspollack
had a great write-up on this. Due to the nature of the controller, it's not as easy as splicing them into the mains. Which bike do you have?
Thanks for the compliment, Brogman. The article in question is this one:
Adding Rivco LED Mirrors to a Victory Cross Country Motorcycle
I wrote that almost four years ago, describing my experience adding Rivco mirrors with built-in front- and rear-facing LEDs. The short answer is that I also added a trailer isolator, because the Vic's ECM is such a fuss-budget nanny. The long answer is ... well, that page, which is verrrry long, because I also used that opportunity to discuss some wiring tips and techniques that have helped me over the years.
Now, in this particular case -- those two mirror sets -- I don't know what the deal is with the bottom threads, and left-hand or right-hand, and metric or H-D, etc. That is, there's also a physical element involved here, in addition to the electrical one, and I have no clue regarding that aspect, in terms of fitment.