Both the seating rim and the seating recess can be of a polygonal shape, with {TAIL ~ the seating rim} fitting {HEAD ~ the shape} of the seating recess of the sample changer 
Both the seating rim and the seating recess can be of a polygonal shape , with { TAIL ~ the seating rim } fitting { HEAD ~ the shape } of the seating recess of the sample changer
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH