{TAIL ~ Left and right valves} are provided in a lower surface of the cover on opposite sides of the seal between the partition and {HEAD ~ the cover} 
{ TAIL ~ Left and right valves } are provided in a lower surface of the cover on opposite sides of the seal between the partition and { HEAD ~ the cover }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD