Liquid is introduced into the bladder via {HEAD ~ a valve} which fits through {TAIL ~ the side wall} of the cylinder  
fits through
Liquid is introduced into the bladder via { HEAD ~ a valve } which fits through { TAIL ~ the side wall } of the cylinder
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH