migraines

I'm currently seeking out a quality hat stretcher. I've been following a few on ebay, but most of what I see are sized 6 3/4. I wear a 7 3/8 long oval, or a 7 1/2. Will a hat stretcher that small do me any good? I measured accrosse the opening of my hats (front to back) at 8 1/2". Will...