Concrete Machine Screw Anchors are female type concrete anchors designed for anchoring into concrete, brick or block. Concrete Machine Screw Anchors have internal machine screw threads. Machine screw anchors are best suited for light to medium duty fastening purposes, are available in 3/16″ (#10), 1/4″, 5/16″, 3/8″, 1/2″, 5/8″ and