The hopper has {HEAD ~ angled sidewalls} 134 which each taper to {TAIL ~ the narrow backfill sleeve width} 126 
taper to
The hopper has { HEAD ~ angled sidewalls } 134 which each taper to { TAIL ~ the narrow backfill sleeve width } 126
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH