Hex head concrete screws, widely known as "Tapcons", are screws made for screwing directly into concrete, masonry block, and brick. They feature a hex head with an indented Philips drive and a blue coating which aids in corrosion resistance. Some applications are fastening conduit and electrical fixtures to walls, anchoring hand railings, metal door frames etc. A hole is drilled to the correct diameter and the screw is fastened into place.