5" Stick On PSA Grit Wet/Dry Autobody Film Sanding Discs, 50-Pack. Special waterproof polyester film aluminum oxide (A/O) pressure sensitive adhesive (PSA) sticky backed paper discs are a solid choice for wet finishing on automotive or other applications needing waterproof abrasives. These polyester discs are precisely stamped and bonded with an industrial grade stick on backing. Film material provides a high strength product and a solid finish with a long working life. These discs work great on metal working applications. Use in wet or dry applications.