An extruded aluminum channel is formed with {HEAD ~ a wide central T shaped groove} and {TAIL ~ narrower outer T shaped grooves} transversely spaced on opposite sides of the central groove 
An extruded aluminum channel is formed with { HEAD ~ a wide central T shaped groove } and { TAIL ~ narrower outer T shaped grooves } transversely spaced on opposite sides of the central groove
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH