3M(TM) Hookit(TM) Microfinishing Film Type D Sheet 366L, 5 in x 2-3/4 in 40 Micron, 1000 per case Precision, micron-graded, resin-bonded, polyester film backing. Aggressive cut with uniform finish. Anti-loading Fre-Cut(TM) coating provides greater efficiency and longer product life. Use on plastic, fiberglass, wood, metal, solid-surface composites.