In {HEAD ~ at least one example}, the base has polygonal guide holes through which {TAIL ~ the stems} extend from the base in the extended positions 
In { HEAD ~ at least one example } , the base has polygonal guide holes through which { TAIL ~ the stems } extend from the base in the extended positions
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH