The position of {HEAD ~ the tray} is then secured with a fastener screwably extending through the second arm into a friction fit relationship with {TAIL ~ the shelf} 
The position of { HEAD ~ the tray } is then secured with a fastener screwably extending through the second arm into a friction fit relationship with { TAIL ~ the shelf }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL