Thanks for the reply, coach Bob. I used the fistgloves in freestyle for a while in my TI early days, then they tore and I didn't buy another pair. After all, naked fist swimming did the job as well, at least for me.
Now that you make me think about it, I guess I never tried fist swimming for backstroke. That's a good idea, I'll try!
Anyway, the purpose of the test I promote in this thread is to give the swimmer a taste of what a perfect anchor (ie zero slip of the hand) feels like.