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