The channel holes H1 may have {TAIL ~ a circular or oval shape} when viewed from the top, and a plurality of the channel holes H1 may be arranged in the form of {HEAD ~ a matrix} 
The channel holes H1 may have { TAIL ~ a circular or oval shape } when viewed from the top , and a plurality of the channel holes H1 may be arranged in the form of { HEAD ~ a matrix }
OTH OTH OTH OTH OTH OTH TAIL TAIL 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 HEAD HEAD HEAD HEAD HEAD HEAD