The second member is removable from the channels by pulling the second member away from {HEAD ~ the channels} to disengage {TAIL ~ the flanges} from the channels 
to disengage
The second member is removable from the channels by pulling the second member away from { HEAD ~ the channels } to disengage { TAIL ~ the flanges } from the channels
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH