We offer 4 sizes of bale tarps. The outer silver reflects the sun while the black on the inside blocks sunlight. Both materials are UV coated (ultraviolet) which helps protect against sun damage, thus giving longer tarp life. We use an extra heavy-duty fabric with rustproof rivets every 18 in around the hem. All 4 corners feature reinforced corners. Works great also as a pool cover, large RV covers and more.