These screws have been designed and tested for attaching our metal pipe flashing boots to corrugated metal roofing. The self-drilling tip makes for extremely quick and easy installation, while the EPDM washer provides a secure seal to prevent any water leakage. This 50 pack of screws will work with roof boots up to Size #8 round and square boots. If you are ordering a #9 or larger roof boot, you will want to order 2 packages of screws per boot to get the job done. As a general rule of thumb these screws are typically installed around 1" intervals from one another.