Copper Coupling (or coupler) is a very short length of pipe or tube used in piping or plumbing, with a socket at one or both ends that allows two pipes or tubes to be joined together.

RUBBER INSULATION (AEROFLEX)
Aeroflex Tube Insulation is a flexible, closed-cell and lightweight elastomeric material designed for insulating cooling and heating lines. The closed cell structure of Aeroflex provides