Downgraded review because I managed to break one of the shifters by forcing the lever.

This pair of shifters runs a Shimano Shadow MTB derailleur on a 10 speed cassette in the rear. I know they are advertised to work on 9 speed derailleurs but I have had no trouble running a 10 speed Shimano MTB rear derailleur and an old Suntour front derailleur on a RaceFace triple chainring setup. The bike is a 3 x 10 speed setup. No problems, no broken parts, good repeatable shifting all the time. That said the little bail on the friction adjusting bolt is not up to the task of tightening the rear derailleur shifter enough not to slip. I have to use a phillips head screwdriver to set this tension. Once set I have never had it come loose over a period of a couple of years now. The front derailleur shifter has been a great performer with no issues. For the price these shifters are a home run in all respects. Are there better shifters out there, yes. Are better shifters worth the price, maybe. Will these shifters get the work done for a very low price, yes. A couple of pictures of these shifters in service on my early 80's Nishiki Sebring.

Falcon Friction Thumb Shifters

These were an experiment. I have an old Raleigh sc30 that I wanted to use for single track, and the frictionshifters I'd strapped to the gooseneck years ago took my hands away from the bars where they really should be for that kind of riding. I had my doubts about something so cheap but they'd at least show me if I liked the location. Well, I do, and these have so far proven durable and quite easy to use, and I haven't yet had to adjust friction. I may order another set or two.
I've had rapid fire shifters on other bikes. I like these better.

Falcon Friction Thumb Shifters