The valve assembly has {TAIL ~ a two part housing}, one of the parts having {HEAD ~ a sight glass} secured therein 
The valve assembly has { TAIL ~ a two part housing } , one of the parts having { HEAD ~ a sight glass } secured therein
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH