Bolt anchor BZ-IG with internal thread for anchoring medium to heavy loads, both in cracked and non-cracked concrete. It combines high permissible loads with small edge and axis distances. An undercut of the drill holes is not necessary. In addition to hexagon screws, the component can also be fastened with countersunk screws, a system consisting of a nut and washer and a standard threaded rod. European Technical Approval ETA-99/0010, including characteristic values under fire exposure up to fire resistance duration R 120. Shock approval from the Federal Office for Civil Protection, Bern, Switzerland.