{HEAD ~ a main cylindrical member}, extending in {TAIL ~ the axial direction} of said housing sections, for movably containing said housing sections, 
extending in
{ HEAD ~ a main cylindrical member } , extending in { TAIL ~ the axial direction } of said housing sections , for movably containing said housing sections ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH