• Be sure that the new mouthpiece will fit on your regulator's second stage, as not every mouthpiece will fit every regulator.
• Many of the regulator mouthpiece styles are available in a variety of materials. The differences in material can effect your comfort.
• Once you find a regulator mouthpiece style that suites you, buy several mouthpieces and keep the spares in your save-a-dive kit.

Regulator Mouthpiece Orifice Sizes

Generally there are four common 2nd stage regulator mouthpiece sizes:

Standard size orifice regulator mouthpiece
- size 1-1/8 inch x 1/2 inch (28.6 mm x 12.7 mm)
Fits: Apollo; Aqua Lung older metal regulators, Conshelf 7 through 21 – snug; Atomic manufactured pre 2005 only and newer T3; Beuchat Evolution, Iceberg and Nitrox, VXT8, VXT Octo, VX4, VX8; Cressi-Sub Ellipse is a 2, XS Compact is snug; Dacor after 1992; IST except Proline is an intermediate; Ocean Master; Pro Sub Avalon; Scubapro S600, S360, S560, R095 and all models before the A700; SEAC; Sherwood most early models – Brut, Shadow, MagnumII, pre 1992 Blizzard + Oasis; Spare Air; Subgear R series and Cayman; Tabata/Tusa not TUSA Imprix.

Intermediate size orifice regulator mouthpiece
- size 1-3/16 inch x 5/8 inch (30.2 mm x 15.9 mm)
Fits: Aeris; Aqua Lung newer, including Titan, Legend, Kronos and Mikron; Atomic pre 2005 use a Standard, newer, larger orifice an Intermediate, if not sure, measure or try on; Beuchat VS3, VS4, VS8, VX10; Dacor Viper + Eagle; Dive Rite including O2ptima rebreather, but not the Jet Stream 4500; Edge HOG + EPIC; Forte; Genesis; Halcyon Rebreather + Regulators; Hollis except 500SE is a Large; Mares (not MARES MR-12-II, III, IV or V); Ocean Edge; Ocean Reef; Oceanic cannot fit Alpha 9 or Omega 3; Odyssey; Scuba Max; Scubapro models after 2010, including A700, C series, G260, R195 and S620TI; Sea Elite; Sherwood Maximus, 1992 and newer Blizzard + Oasis, SR1; SPORASUB; SUBGEAR SG50, SG30, SG10, Aruba and Bonaire, Tigullio, Tilos; XS SCUBA (previously IDI, Osprey is a standard).

Large size orifice regulator mouthpiece
- size 1-5/16 inch x 11/16 inch (33.3 mm x 17.5 mm)
Fits: Apeks; Dive Perfect; Hollis 500SE; and Zeagle 2nd stage regulators. Plus many rebreathers, including Golem Shrimp BOV; Hollis Prism+Explorer; ISC Megladon; Kiss Gem; Poseidon (snug fit); and Titan.

Extra Large size orifice regulator mouthpiece
- size 1-7/16 inch x 13/16 inch (36.5 mm x 20.6 mm)
Fits: Poseidon regulators.

Tech Tip: Inspect Your Regulator Mouthpiece

When is the last time you gave any thought to your regulator mouthpiece? Our service technicians tell us one of the most commonly damaged parts they discover during routine maintenance on a regulator second stage is the mouthpiece itself.

Many divers bite down much too hard on the mouthpiece, particularly if it is a poor fit. Besides the fact that biting too hard may cause the diver to climb out the water with an annoying headache, we even find bite tabs completely missing from the mouthpiece where they have been literally 'chewed off'. If that's happening to you, consider trying a different style of mouthpiece.

A more subtle damage often responsible for second stages 'breathing wet' is an almost invisible tear in the mouthpiece, just past the mounting lip on the second stage body near or under the cable tie. These often can't be seen unless you stretch the mouthpiece by hand and inspect in bright light.