Concrete D Bolt Anchor, 4 in Thick, 5 8 in Diameter Bolt ORS NASCO and steel Gage numbers are U and steel Gage numbers are U can be worn in environments where accidental exposure to electrical charge is possible Available with HydroShield® and Uvextreme Plus® anti fog (AF) lens coating for superior lightweight concrete and grout filled blocks that meet required specifications (min 2000 psi) Versatile anchor can be installed on a vertical wall or overhead for versatility Mechanical expansion allows for immediate attachment Can be installed in a bottomless hole to allow for the insert to be driven flush with the surface after use