The well cap cable holder creates a water- and air-tight seal between the top of the well and the instrument. The cable holder is an ideal accessory for use in soil vapor extraction applications. Pressure rating: 60 psi maximum at 20-25°C (68-77°F); 30 psi up to 50°C (122°F). 2.75 in. diameter at its widest point, 1.5 in. NPT.