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