The Heat Pump System is specially designed for copper refrigeration lines of 3/8 – 3/4” , with 4 rings total in a box.
Two of those rings go on compressor outside the house and 2 on air handling units in the house.
There are 2 copper lines between heat pump and air handler. Each copper line has a Magnetizer ring at each end, b/c the system works on reversing the flow and we always want to treat the input to those 2 units (air handler and heat pump), hence four rings altogether.
For more information please see A/C Split unit and visit A/C Split Unit & Refrigeration section.