Depends on what you like. If you're going uber accurate, they are like the ones in firelbadejedi's post, but if you just want strength and don't want to search high and lo for the perfect ones, since they wont be showing anyway, I just use Line 24 snaps. You can find them at Tandy, however I get mine off eBay. You can save a bundle getting it from there. I usually buy packs of 100-200.