Oh crap, didn't know these existed. I was looking at a $100+ automatic indicator cancelling module. But it was too expensive. So as an alternative, I thought that as I regularly check my mirrors a little LED light on the edge of the mirror would be handy, and get my attention.
So I went up to Jaycar and spent a whole $6.00 each on two little red LED lights. And fitted them same as the instructions mentioned in this post. They work a treat and cheap. You could fit more than one on each mirror if you wish, which I am considering. I did want amber, but they only had red, and in hindsight I think is better as cars behind me will see the red light flash and attract their attention (only a minute possibility and wishful thinking there).