The Walraven WT7 in the range of M6, M8, M10, M12, M14, M16 and M20 is an anchor made of galvanised steel. The Walraven WT7 SST/A2 and WT7 SST/A4 in the range of M6, M8, M10, M12, M16 and M20 are anchors made of stainless steel of grades A2 and A4 respectively. The anchor is installed into a predrilled cylindrical hole and anchored by torque-controlled expansion. The anchorage is characterised by friction between expansion clip and concrete