{HEAD ~ An assist mechanism} aids movement of a retractable unit reciprocally moving between an open and a closed position and includes a pressing device, {TAIL ~ a stopper mechanism}, an engagement member, a catch portion, and a release member 
includes
{ HEAD ~ An assist mechanism } aids movement of a retractable unit reciprocally moving between an open and a closed position and includes a pressing device , { TAIL ~ a stopper mechanism } , an engagement member , a catch portion , and a release member
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH