{HEAD ~ The wafer transfer device} has {TAIL ~ a first unit} with a plurality of first slots for receiving a first group of semiconductor wafers and a second unit with a plurality of slots for receiving a second group of semiconductor wafers 
{ HEAD ~ The wafer transfer device } has { TAIL ~ a first unit } with a plurality of first slots for receiving a first group of semiconductor wafers and a second unit with a plurality of slots for receiving a second group of semiconductor wafers
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH