L.H. Dottie 14H234 1/4'' x 2-3/4'' Slotted Hex Washer Head Concrete Screw Anchor. Concrete Screws are tempered masonry screws designed for long lasting performance and superior holding strength. Due to their unique thread design, they are the ideal fastening solution for light to medium duty applications in concrete, brick, masonry block and wood base materials. They are manufactured with a gimlet point that taps it's own threads while drilling into the base material. Common applications for this fastener include the attachment of electrical boxes, light fixtures, and masonry base materials.