This Apeks brand mouthpiece in a color 4-Pack (Blue, Yellow, Green, Red) includes one each of all four colors in standard size with { 1.2 x 0.65 in | 3.0 X 1.6 cm } opening for the second stage orifice that fits most all brands of regulators except Poseidon. The ergonomic bite-wing design works equally well with either up or down orientation in the mouth and all the edges have been rounded ensuring it’s comfortable to wear even during extended dives. Brightly colored mouthpieces are more than just a fashion statement, many technical divers use them on stage bottles as an additional way of coding gases. Available in a hypoallergenic flexible silicone, we also include a tie wrap to attach the mouthpiece to your second stage.