{TAIL ~ The base} is perforated by {HEAD ~ at least one port} whose length is very much less than the mean diameter and the base, external to the box is capped by a flexible and sealed bellows adapted to form with it a pocket of variable volume 
{ TAIL ~ The base } is perforated by { HEAD ~ at least one port } whose length is very much less than the mean diameter and the base , external to the box is capped by a flexible and sealed bellows adapted to form with it a pocket of variable volume
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH