TIMCO Wing-Tip S/D Screws Countersunk PH Bi-Metal 5.5 x 85 PK 100 are precision-engineered self-drilling screws built for heavy-duty fastening of timber to steel or other metal structures. Featuring a bi-metal composition, these screws deliver the perfect balance of strength, corrosion resistance, and long-lasting performance. The wing-tip design enables effortless drilling through wood into metal without pre-drilling, while the hardened steel tip ensures fast penetration and secure fixing. The countersunk Phillips head offers a clean, flush finish, making these screws ideal for professional builders and contractors working on cladding, framing, or structural projects.