A pressure monitoring device in accordance with the present invention comprises a housing 1 within which are provided an air inlet 2 and an air outlet 3. Connecting the air inlet 2 and the air outlet 3 is an air passage way 4 which includes a pressure take off point 9. The air inlet 2 includes' a threaded bore section 2a into which is screwed a coupling device 7 for coupling with the air outlet of a compressed air supply. The air outlet 3 is also configured to receive a coupling device 8 for coupling with the air inlet of a paint spray gun. A digital pressure gauge 5 is housed in a top surface of the housing 1 as shown in the figures. The gauge samples air pressure at the pressure take off point 9 through conduit 9a. Screw threaded into a bore 11 in the housing is a needle valve 6 which can be adjusted by means of valve adjustment means 10a, 10b to move further towards or away from the pressure take off 9.