| 摘要 |
A seat cushion features an inner core of an open-celled compressible foam material hermetically sealed within a first inner cover which is of a size to fit loosely about the inner core. An outer cover is of a size and shape substantially as that of the inner core and is nominally larger to allow the material of the inner cover to shift within the space between the inner core and the outer cover. A tube incorporating a valve leads from the space within the inner cover through the covers to the atmosphere. The cushion is naturally self-inflating when the valve is open so need not be blown up by the user with this or her lungs or other air source. A sitter on the cushion can adjust its compressibility by opening the valve, or deflate the cushion entirely for storage or for portability, then close the valve to maintain the cushion deflated.
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