1/2" NPT Piggyback Filter Regulator Unit Max Supply Pressure: 250 PSI, Max Operating Pressure: 150 PSI 106 SCFM, 10 Micron Element Standard Piggybacks are compact and most effective when space is constrained Brand new 1/2" compressed air pressure regulator & filter combination with gauge and free wall mounting bracket Manual Drain & Metal Bowl, Includes 0-300 Gauge & Bracket There is 1/2" female npt threads on each side for your main compressor line coming in and going out, and a 1/4" female thread on the outer side for your gauge as shown in the pictures.