The spring 34 may be formed of {HEAD ~ a variety} of steel materials and {TAIL ~ alloys} 
of
The spring 34 may be formed of { HEAD ~ a variety } of steel materials and { TAIL ~ alloys }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL