Also provided are plates to form zigzag air passages by blocking {HEAD ~ a space} between {TAIL ~ the inner cover} and the outer cover 
between
Also provided are plates to form zigzag air passages by blocking { HEAD ~ a space } between { TAIL ~ the inner cover } and the outer cover
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH