Each panel has markings on its side to indicate {HEAD ~ the wind speed} required to effectuate {TAIL ~ its unfurling} 
required to effectuate
Each panel has markings on its side to indicate { HEAD ~ the wind speed } required to effectuate { TAIL ~ its unfurling }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL