Although all of our tarps with the exception of the blue utility tarps are considered heavy-duty, the silver tarp is the best color for total sun block. Comprised exactly the same way as all the other heavy-duty poly tarps, the silver tarp has an added feature for eliminating sun penetration. Each silver tarp has what is called a black scrim layer placed between the laminated sheets of plastic. This scrim layer prevents any light from penetrating the fabric. All of the other heavy-duty poly tarps allow the natural sunlight to come through the fabric while still providing 95% UV protection.