Concrete 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.

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