The inner cylindrical member 40 has an outer shape and a cross section, as shown in FIGS 3A and 3B. A pair of {HEAD ~ housing portions} 40a for {TAIL ~ housing} the rear cylindrical members 4 are juxtaposed 
The inner cylindrical member 40 has an outer shape and a cross section , as shown in FIGS 3A and 3B. A pair of { HEAD ~ housing portions } 40a for { TAIL ~ housing } the rear cylindrical members 4 are juxtaposed
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH