These heavy-duty, yet lightweight tarps weigh 25% more than most blue tarps. A high-density polyethylene weave ( 10 strands vertically, 10 strands horizontally per sq. inch) is chemically sandwiched between two coatings of waterproof polyethylene sheets. Aluminum grommets are spaced about every three feet. Double stitched and welded, rope reinforced hems. For more demanding applications, we suggest the green/black tarps. Reinforce stress points with TARP TAPE, BAC-TG34 ( order#146670)