This feature will noticeably reduce jaw fatigue some divers experience when holding a regulator in their mouths for extended periods. This popular mouthpiece fits all brands of regulators we sell and most other brands, except Poseidon. Great for CCR use as well, as long as it fits your DSV. This is the genuine OEM product and not a generic copy. Available in a hypoallergenic firm flexible silicone, we also include a special low-profile tie wrap that lays very flat to attach the mouthpiece to your second stage.