Using super high density polyethelene, we can cut boards up to 1" in thickness and offer board lors in white, red, green . 1/4 inch waterproofing high density plastic board for Horse . Product Description. Marine Board HDPE (High Density Polyethylene) Plastic Sheet 1/4" x 24" x 48" White lor Textured. High density polyethylene (HDPE) is used in