Great but defects

Quality is generally great because of the durable, waterproof material used, but 5/20 of my sheets had imprints -- they looked as if pieces of sand were stuck in between the sheets. I obviously can't sell those sheets with the defects -- so I'm at a loss of $. Only worth it if you're ordering 100 or more I suppose. But didn't expect so many defects. Disappointing. Needs better quality check.