The slight reduction in the diameters of portions of the valve may be characterized as somewhat of {HEAD ~ a collapsing motion} which can occur around the distal end of the lid seal post 502 and which further facilitates the sealing of {TAIL ~ the valve} 345 by the lid seal post 502 
The slight reduction in the diameters of portions of the valve may be characterized as somewhat of { HEAD ~ a collapsing motion } which can occur around the distal end of the lid seal post 502 and which further facilitates the sealing of { TAIL ~ the valve } 345 by the lid seal post 502
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH