To define a stable position of {HEAD ~ the draft shield element} on {TAIL ~ the sample changer}, the seating rim of the draft shield element sits in a matching seating recess of the sample changer 
on
To define a stable position of { HEAD ~ the draft shield element } on { TAIL ~ the sample changer } , the seating rim of the draft shield element sits in a matching seating recess of the sample changer
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH