Series A-320 Instrument Enclosure protects instruments in all applications. The weatherproof enclosure is water tight and corrosion resistant. The A-320-A fits standard Magnehelic® size instruments (4-9/16" diameter) and the A-320-B fits standard 3000MR Photohelic® switch/gage size instruments (4-13/16" diameter). Both models include silicone tubing, gage barbs and mounting hardware.