The detector includes {TAIL ~ a microswitch} having a sensing arm which contacts a center portion of {HEAD ~ an elastic membrane} 
The detector includes { TAIL ~ a microswitch } having a sensing arm which contacts a center portion of { HEAD ~ an elastic membrane }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD