I do know that the "plain" Steel Fingers does reduce tendonitis pain. I have no experience with the wrist support version of them. Sorry.

Used both the Steel Fingers by itself and the Steel Finger with the wrist support.  The Steel Fingers by itself is a little clumsy to put on but much easier to put on when installed on the wrist support.  Not a real good wrist support imo but the Steel Fingers helps relieve pain, keep the lift fingers in a good lift position and helps make the lift more consistent.

These steel fingers sound like something I might like to try. Does anyone have the information on who makes them and where I might purchase them?

This is the only place of which I am aware:
http://steelfingers.com/