Amazon may not be selling these anymore from the looks of it but, should they come back, I would hope that the quality would improve.  My set broke after one use ... or, I should say one "foot" broke and the other is a bit wonky.  The one that broke can be opened enough to at least hold the boot from shrinking but its stretching days are over.  The other one can still stretch but it looks like it's likely to break like the other one soon.  What's breaking is a section on the back of the "foot" on the upper side where the two sides are held in register with each other but allowed to separate slightly.  The problem is that there's a fat "pin" that holds the screw, the pin goes through the sides of the foot perpendicular to the screw, but the pin is too short.  Once the foot is spread, the too short pin has a tendency to break out of the holes in the foot because there's not enough wood to still hold the wood.  And I do mean "break out" as the pins tend to crack the wood as they come loose.

Anyway, they have managed to stretch one pair of hiking boots so they do work.  It just appears that if I have another set of boots to stretch, I'll need to buy another set of stretchers.