Here's what I bought. It seems like each color of mouthguard has a different price, so you'll need to click around to find the cheaper ones (the one I bought has an extra 25% off at checkout).

I specifically bought the Gel Nano Convertible because I used to have one (before I lost it on a trip), and it fit waaaaaaaay better than the Nano 3D Convertible I bought to replace it.