Dritz Sew-On Snaps, Size 1 - Nickel Plated Brass - 8 Ct.

These are well-made buttons with a nice firm snap, but I don't know why the dimensions aren't listed anywhere! The top half of a size 1 snap (which seems to be totally different from size 1/0...) is 10mm in diameter, and the smaller bottom half is 9mm. I bought these to close the necklines of a couple wrap dresses, and they work well for that purpose. I think size 1 is about as small as I could go while still being able to pull the snap apart easily with my fingers.

Sooo small. They work, but they're the size of the small buttons you might see holding down the collars of men's collared shirts. Thats how tiny they are. Just be forewarned.