This is a Johnson Controls limit switch # P20BB-1C
High pressure control with SPDT contact unit and automatic recycle. The screws and connectors are supplied and the red and blue terminal locations only. 36" CAP with 1/4" Sweat Conn
Red to blue contacts open at 40 PS I G. on pressure drop . Range of cutout is 7 to 125 PSI.
(picture is similar and not actual part number of control)