Red Head Dynabolt 303 Stainless Steel Phillips Flat Head 1/4 X 2-1/4 Inch Anchor feature a split expansion sleeve over a threaded stud bolt body and integral expander, nut and washer. The anchor diameter equals hole diameter, with 1/4 - 3/4 inch diameter anchors available, up to 6-1/4 inch length. The sleeve design improves holding power. These sleeve anchors provides full 360 degree hole contact over large area and reduces concrete stress, with a heavy-loading capacity. They are preassembled for faster, easier installations and can be installed through object to be fastened. No pre-spotting of holes necessary. The anchors are stainless steel and should be installed with carbide tipped hammer drill bits. Available in hex head and six other head styles. Specs: Anchor Diameter and Drill Bit Size - 1/4 inch; Effective Anchor Length - 2-1/4 inch; Bolt Diameter - 3/16 inch; Threads per Inch - 24; Min. Embedment - 1-1/8 inch; Max. Thickness of Material to be Fastened - 1-1/8 inch.