The GRK Caliburn Concrete Screws Contractor Kit includes 5 different sizes of Caliburn Concrete Screws along with 3 size bits. The screws come in sizes ranging from 9/16" x 2 3/4" to 1/4" x 1 3/4" and feature a star head style. This kit is designed for industrial use in the construction and fastening industry, with the brand being GRK and the model being GRK Caliburn. This versatile set of screws and bits offers a variety of sizes to suit various needs and projects.