The runner is accommodated at {HEAD ~ the fixing portion}, and is capable of up and down sliding movements at {TAIL ~ the fixing portion} 
The runner is accommodated at { HEAD ~ the fixing portion } , and is capable of up and down sliding movements at { TAIL ~ the fixing portion }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL