I found a pack of these at Walmart last week in the clearance section only one pack- and it's four bikinis to a package. Nylon/spandex blend, so they are stretchy and have a silky smooth feeling to them. They fit well and and are comfortable. They will provide good coverage as long as you don't get hard. Ideal for both underwear and swimwear.
Appearance-wise, they can pass as men's bikini briefs, in fact they look like the old style jockey skants from the 1950s.