The Tolsen 54177 is a self-drilling screw designed for securing metal or aluminum panels, roofs, and facades. These fasteners feature a 4.2 mm diameter and a length of 25 mm, allowing you to skip the pre-drilling step and speed up your installation process. Each screw is finished with a zinc plating for better corrosion resistance and is equipped with a Phillips drive and a countersunk head that sits flush with the surface. This pack contains 500 pieces, making it a practical choice for contractors or homeowners working on larger structural cladding projects.