MEGAFastener Dura-Screws - Zinc Plated Case Hardened Steel Hex Washer Head Self Drilling Sheet Metal Dura-Screws are primarily used to construction, manufacturing, engineering, assembling and so on. Thread Type: Self Drilling Sheet Metal Dura-Screws. These super-handy self-drilling screws were designed to fasten and secure two pieces of material (metal-to-metal or metal-to-wood, metal-to-plastic, etc) together, without the need for pre-drilling). Hex washer self drilling screws have a drill bit point. A hexagonal head for use with a wrench. They are ideal use for wood, metal or other tough materials and known for their effecient application performance and endurance.