Contractor Friendly Gutter Screws. The Best Gutter Screw on the Market! One of our hottest selling products is our #12 self piercing screws which have 1/4" heads that are 28% taller than the standard. They also have a #12 washer under the head instead of the standard #8 washer. This helps to ensure that the screws dont slip out of the drivers, better tool engagement and increased tool life.