66M to 4 Pin Modular Adapter (USOC)
Fits over the pins on a standard 66M Block (won't fit on a 66B Block). Brings the pins out to a 4-Pin Modular Jack.
NOTE: because of the size, you can't use these Adapters on adjacent lines (pins) on the 66M Block.
4 Pin Modular Jack (RJ-14)