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