{HEAD ~ Each} of the casings includes {TAIL ~ a coverable opening} through which the electrolyte solution within the cell is replaceable 
{ HEAD ~ Each } of the casings includes { TAIL ~ a coverable opening } through which the electrolyte solution within the cell is replaceable
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH