This............http://dooropenersandmore.com/transmitter-solutions-390ged21k-mini-remote
is what I purchased hoping my old remote was bad and not wanting to buy a $70 remote to find out. The remote was not the problem, it was the mother board in my opener. I ended up replacing the entire opener and this Firefly 1 button key chain transmitter doesn't work with my new opener.
This is a 390 1 button key chain opener and works with green learn light openers. You can read compatible openers on the web site.. Paid $13.25, will take $5 for it. Brand new
The unit I had was a Craftsman opener. The company says should work with any 390 MHz green light capabilities.