I don't recommend....
Not very strong, spring has no choice but to stretch out.  The spring is NOT heavy duty at all.  Although they give an inch to the waist (but..... at the same time the spring stretches out and distorts while attempting to pull up the zipper).  Because they are springs it is very difficult to hold the top firm in order to pull the zipper up.  I thing the cloth ones would work much better. Again, I got what I paid for.
Rating: 2 stars