The parts to a compression fitting are a compression nut, a compression ring, and a compression seat. A compression fitting is a coupling that attaches two pipes together quickly without having to worry about leakage. This type of fitting works well for places that you can not solder.

You put together a compression fitting by sliding the nut on to the pipe, you then place the pipe in to the fitting with the ring on the end, this ring is made of rubber, you then attach the compression seat to the other pipe, then you place the pipe with the ring fitting into the compression seat. When both pipes are connected you will tighten the compression nut, when you tighten this it presses the ring into the seat creating a water tight seal.

Remember that compression rings can not be removed once they are attached, the pipe will have to be cut and a new ring installed. This may be an issue if there is not that much pipe to begin with, if this is the case the whole pope may have to be replaced.

Never over tighten a compression fitting, this may cause damage or cracking to the pope especially when working with plastic pipe.