The block member moves from a first position to a second position by contact with the slider sliding in {HEAD ~ a sliding direction} to block and open {TAIL ~ the air passage} 
The block member moves from a first position to a second position by contact with the slider sliding in { HEAD ~ a sliding direction } to block and open { TAIL ~ the air passage }
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 HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL