said {TAIL ~ second wearable display} has a same constitution as {HEAD ~ the first wearable display comprises}: 
said { TAIL ~ second wearable display } has a same constitution as { HEAD ~ the first wearable display comprises } :
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH