In the various installations shown in FIGS 18 to 25, {HEAD ~ the lengths} of {TAIL ~ the covers} may vary considerably, depending on the concepts of the tooling and stocking 
of
In the various installations shown in FIGS 18 to 25 , { HEAD ~ the lengths } of { TAIL ~ the covers } may vary considerably , depending on the concepts of the tooling and stocking
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH