The thickness of the thick walled portion is set to be {TAIL ~ about 1.4 to 1.6 times the thickness} of {HEAD ~ the thin walled portion} 
The thickness of the thick walled portion is set to be { TAIL ~ about 1.4 to 1.6 times the thickness } of { HEAD ~ the thin walled portion }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD