The AnchorMark AMDEX concrete screw is a type of anchor made of carbon steel and stainless steel (bimetal). The anchor is made of carbon steel for sizes 6,8,10,12 and 14 and of stainless steel for sizes 6,8, and 10. Both of them are screwed into a predrilled cylindrical drill hole. The special thread of the anchor cuts an internal thread into the member while setting. The anchorage is characterised by mechanical interlock in the special thread.