Assertion: snorkel's mouthpiece | /r/MadeOf | at least one chamber
Facets:
value: within it
type: LOCATION
Source sentences:
text: It has been discovered, according to the present invention, that if a mouthpiece is designed to fit into the user's mouth and contains within it at least one chamber which extends to at least one hollow breathing tube which is designed to conform to the shape of the side of the user's face and head and which hollow tube extends upwardly and backwardly behind the user's head and just above the user's ears.