The belts tend to center themselves toward the high points of {TAIL ~ the crowns}, but are narrow enough to leave edges of transported envelopes free for {HEAD ~ registration} 
The belts tend to center themselves toward the high points of { TAIL ~ the crowns } , but are narrow enough to leave edges of transported envelopes free for { HEAD ~ registration }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD