{TAIL ~ The reservoir} is preferably {HEAD ~ a replaceable unit} which is available commercially and which is fitted with a removeable cap to adapt it to the system 
{ TAIL ~ The reservoir } is preferably { HEAD ~ a replaceable unit } which is available commercially and which is fitted with a removeable cap to adapt it to the system
TAIL TAIL TAIL TAIL TAIL TAIL 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