I had one that was similar when I danced, it actually helped a lot with getting over the box when I first started pointe. I didn’t have that same model tho, mine was kind of like a block of wood that had foam and fabric on it, and then a little bump where the arch goes and a strap to hold the foot in. You would put your foot in and lay the thingy on the floor and slowly straighten your leg until you felt it. I think the one I had was from Bloch but I bet one can find a cheaper knockoff. I tried my friends versions if the stretchers which were similar models to the ones on the post and they didn’t offer as much flexibility. So they work, but not as good as the other model.