The assembly 1, wherein {HEAD ~ the casing} and {TAIL ~ the collars} are made of composite material 
The assembly 1 , wherein { HEAD ~ the casing } and { TAIL ~ the collars } are made of composite material
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH