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