{HEAD ~ The key} 1320 is sleeved on the recessed portion 1312, and a surface 1322 of the key 1320 is more depressed than {TAIL ~ the protrusion portions} 1314 
{ HEAD ~ The key } 1320 is sleeved on the recessed portion 1312 , and a surface 1322 of the key 1320 is more depressed than { TAIL ~ the protrusion portions } 1314
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 OTH