It appears no one seems to know too much about this aid. Actually you don't even know you have it on - I've been wearing it over a BB jacket as it's been cool and keep it very snug. Because the L wrist is firm, the R wrist stays bent. My wrist is still "intact" and I've taken a few full swings to try it out. I don't think injury is an issue. I hit 200 chips/pitches tonite with it on and then will practice the impact bag drills in the house with it off.
I'll keep using it for the next 6-8 weeks as a guinea pig and let you know my results. And keep in mind I have been a wrist hitter for 45 years; self-taught and thought you were suppose to use your wrists! So I have a lot of "unlearning" that I'm working on. This aid (hopefully) will give me the correct feel of the proper mechanics. I will eventually move up to the Tac-Tic and I suppose I could even alternate them now - 50 balls with WristFirm and 50 balls with Tac-Tic, etc.