 Zelmans, it works not only in your mouth, then it goes down to your gut and really goes to work. I mean, this is on a level that you have not seen before. Money-back guarantee, I've never seen anybody use it. Free shipping if you order multiple packs, and trust me, you're going to want to order multiple packs. And I've known these folks at Zelmans for over 30 years, and I actually bought into this company. That's how much I believe in them.