The brilliance of a Z press tool is that you can change jaws very quickly and easily enabling you to work on different plumbing mediums in seconds with just one tool. M and V-profile jaws are designed to be used on copper, stainless steel and carbon steel systems. TH and U-profiles jaws are designed to be used on plastic multilayer systems that are commonly found in domestic plumbing and underfloor heating systems. It is up to you make sure you are using the correct profile jaw for each type of fitting and plumbing medium.