{HEAD ~ The front cover} is movably mounted on the base and has a rear surface and a transverse slot formed on {TAIL ~ the rear surface} 
{ HEAD ~ The front cover } is movably mounted on the base and has a rear surface and a transverse slot formed on { TAIL ~ the rear surface }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL