PPR end caps are used to push or thread over the outside of a part, while PPR end plugs push or thread inside the part. Caps and plugs prevent dirt, dust, moisture, liquids and any other contaminants from entering the opening during manufacturing, masking, storage and transportation.

A thread plug is a male threaded fitting which seals the end run of a pipe when fitted into a female threaded fitting. An end cap is a female threaded fitting and is threaded over the end of a piece of pipe to seal it off.

A cap is used to block off a piece of tubing at the end. With a cap installed, you can fully pressurize your system. The cap is a complete Swagelok assembly, with a nut, a front ferrule, a back ferrule, and a fitting body. The difference is that the fitting body is blank rather than open.