Self-tapping screws are fasteners that have a tapered point allowing the screw to thread itself into a pre-drilled hole, though some softer materials may not require pre-drilling. Self-piercing screws are a form of self-tapping screw that have sharper point to pierce through thin metal without pre-drilling, or to easily enter softer materials. The threads taper down to the point, allowing the screw to form threads into the material as the screw is installed. Phillips modified truss head screws have an oversized, flanged head, and are often called K-Lath screws . Phillips modified truss head self-piercing screws listed here have a zinc plated finish for added corrosion protection.