During cooperation of {HEAD ~ the cam elements}, the engagement elements engage for affecting resilient displacement of the stirrup from its neutral position during initial forward displacement of {TAIL ~ the boot member} 
During cooperation of { HEAD ~ the cam elements } , the engagement elements engage for affecting resilient displacement of the stirrup from its neutral position during initial forward displacement of { TAIL ~ the boot member }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL