NO 87, 67 and 7 Automatic Air Vents are designed to vent the accumulation of troublesome air wherever it can be trapped. These non-ferrous automatic air vents are 4-3/4 in x 2-1/4 in, 3-3/16 in x 1-1/2 in, and 4-1/6 in x 2-3/16 in(height and width), respectively, and are rated for a maximum operating temperature of 240 deg F at pressures of 150, 35, and 75 PSI, respectively. The No. 87 has a combination of 1/2 in FPT / 3/4 in MPT connection, whereas No's. 67 and 7 have 1/8 in MPT and 1/8 in FPT connections, respectively.