MKT Fastening Sup-R-Sleeve acorn nut sleeve anchor is made of 304 stainless steel. Length of sleeve makes anchor more forgiving than a wedge anchor and induces less stress on the substrate. Can be used in solid or hollow masonry. Works in a bottomless hole. Required hole diameter equals anchor diameter. Supplied assembled with 4 possible head styles. Concerns: do not over-torque. Approvals/listings: G.S.A. Spec FF-S-325C, Group II, Type 3, Class 3. 1/4-inches Hole diameter. 1-1/4-inches Maximum thickness materials to be anchored. 1-inches Minimum embedment. 3/16-inches Diameter thread stud to set. 5-8 Required torque. Measures 1/4-inches diameter by 2-1/4-inches length. Ultimate tensile in 2000 PSI concrete: 1356 pounds, ultimate tensile in 3500 PSI concrete: 1400 pounds and ultimate tensile in 5000 PSI concrete: 1640 pounds. Ultimate shear in 2000 PSI concrete: 792 pounds, Ultimate shear in 3500 PSI concrete: 920 pounds and ultimate shear in 5000 PSI concrete: 1148 pounds.