(under subclass 171) Head coverings provided with an air passage, smaller in cross-section than the head dimensions, combined with an adjustable or removable means to either (1) open, or (2) substantially close off or cover the passage.
SEE OR SEARCH THIS CLASS, SUBCLASS:
171.1, for head coverings in which the crown consists of a dome portion and a head-surrounding portion, said portions being bodily movable relative to each other to provide an open area therebetween upon separation of the portions and to close said area when the portions are brought together.
