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