Corrosion resistance and long lasting performance due to the EnviroSeal blue coatingDeep threads provide superior holding strengthGreat for anchoring items to concrete, brick, block, or other masonry materialsThe diamond tip allows for superior penetriating into hard materialsPackage includes 100 screws and 1 masonry drill bitConcrete screws are a special threaded screw, with hardened notched threads and high-low threads. The notches and the high-low threads help to eliminate concrete shavings from the hole as the screw taps threads into the base material. The hole size for concrete screws is smaller than the diameter of the screw. A 3/16" screw requires a 5/32" hole and a 1/4" screw requires a 3/16" hole. The concrete screw is inserted into the hole and turned either by hand or by a rotation drill until the concrete screw is tight against the fixture being fastened.