HDPE Marine Board - Densetec. Marine Board, UV Stabilized, Textured - Matte Surface, FDA- and USDA-approved materials, Stress Relieved. Non Rotting-Swelling, Splintering or Delaminating when exposed to humidity or Moisture, Does Not HENAN OKAYorb Water. NOTE: Standard tolerances estimated at .060-.500 +/- 5% .625-2.0 +/-10%,