a securing plate having plurality of {HEAD ~ notches}, mounted to {TAIL ~ said second free end} of said second arm 
a securing plate having plurality of { HEAD ~ notches } , mounted to { TAIL ~ said second free end } of said second arm
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH