Tapcon 1/4-in x 3-3/4-in Head Blue Concrete Anchors (75). Tapcon is the original masonry anchor that cuts threads into concrete, brick, or hollow block. Use Tapcon 1/4 in. x 3-3/4 in. Climaseal steel hex-washer-head indoor/outdoor concrete anchors (75-Pack) for fastening applications in masonry, such as attaching electrical equipment, 2 ft. x 4 ft., downspout straps, hose reels, flag poles