We offer 3 sizes of port plugs...but most regulators only have 2 size plugs on their first stages. Port plugs can be either a high pressure (HP) port plug or a low pressure (LP) port plug. All O-rings on these plugs are oxygen compatible and Nitrox ready. The DGX silver plugs are industry standard chrome plated brass, the DGX black plugs are brass with PVD coating the industry calls "black chrome". The Omniswivel brand plugs are stainless steel.

The most common size port plug for HP ports (SPG, air integrated computers, transmitters) is 7/16-inch. Some early vintage (perhaps better described as 'antique') first stages have the high-pressure port size same as a 3/8-inch low-pressure port, but these are extremely uncommon (and dangerous.)

The most common size port plug for LP ports (BC inflator hoses, Regulator hoses) is 3/8-inch. This size is used on just about every brand of regulator made.

There are a few unique regulators available with one oversized 1/2-inch LP port. This 1/2-inch size is not common and is usually found as an option on some Apeks, Aqualung (US Divers) and Mares brand uncommon first stages. We recommend the Omniswivel brand 1/2-inch LP port plug for use on the rare Apeks DST swivel first stage with both a 1/2-inch port AND with a 5th port upgrade. See also Regulator Hose, Oversized LP (1/2-Inch).

Most LP and HP port plugs use either a 3/16" or 5/32" hex key for installation and removal. SAE 3/6" is approximately 4.78 mm and SAE 5/32" is approximately 3.97 mm, so metric 4mm, 4.5mm or sometimes 5mm hex keys will also work. Replacement O-ring AS568 sizes are: 013 for Large Low-Pressure Port/Hose (1/2 UNF), 012 for High-Pressure Port/Hose (7/16 UNF), and 011 for Standard Low-Pressure Port/Hose (3/8 UNF).