Thus, the lip 14 a functions as a first weir for receiving {TAIL ~ the kinetic energy} of rain water, thereby preventing {HEAD ~ rain water} from penetrating into the interior of the groove portion 12 
Thus , the lip 14 a functions as a first weir for receiving { TAIL ~ the kinetic energy } of rain water , thereby preventing { HEAD ~ rain water } from penetrating into the interior of the groove portion 12
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH