The D4TM is a double-stop device with an auto-lock function (which is activated whenever the operator lets go of the handle) and a panic brake which is not overly sensitive in normal use. 

The D4 cam is made from a super hard solid Stainless Steel and is highly wear and corrosion resistant. The D4 is compliant with CE Standards, NFPA T and ANSI Z359.4 for the worldwide Rope Access and Rescue markets which typically use 10.5mm/11mm ropes.