This step drill by make-2-fit is constructed of hardened steel and features two diameters in one, for specifically for use when installing aluminum screen plunger bolts. It is used to drill 2 different diameter holes in one single pass for installation of screen plunger bolts into the screen frame. The drill diameters include a 1/8 inch and a 7/32 inch bit diameter, and the larger diameter is only intended to pass one layer of the hollow aluminum screen frame. For best results, follow the installation instructions included with each package.