| 摘要 |
A protective cover which is generally in the form of a flexible bellows construction secured at each end by collars in order to define an interior space includes vent means. Thus, when the cover is deformed, the volume within the interior is altered by aspiration or evacuation through the vent means. The vent means includes a vent element in order to allow air or fluid transfer into and out of the interior but prevent ingress of contaminants such as grit and water to the interior.
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