I've used these in making several small hip packs and they prove sufficiently strong for this use and very handy for all to use. The magnet snaps into place every time without issue and is quite strong.
My only issue was that one half fell and I thought it was lost. Nope, found it several months later inside my sewing machine cabinet attached to the metal hinge...
My application required one-handed use, and Magic Buckle did the trick. Everyone I have put it in front of had been able to intuitively figure out how to use it. Great product!
Strong magnet, a personal favorite buckle.