Box of 25 - 1/2 - 13 x 2 3/4 Stud AnchorStud Type Anchors—SPECIFIED FOR ANCHORAGE INTO CONCRETE. Bottom-Bearing, Hammer-Driven Anchors Stud Anchors feature a bolt body and pre-assembled expander plug. Anchors should be installed with carbide tipped hammer drill bits made in accordance to ANSI B212.15-1994 Anchors are tested to ASTM E488 criteria and listed by SBCCI. Anchors are listed by the following agencies as required: UL and FM