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