Easy-to-operate cylindrical lock

A lock comprising:

• an inner assembly including an inside lever handle, an inside rose, an inside rose liner, and an inside spindle, the inside lever handle having a rectilinear section for manual operation;
• an outer assembly including an outside lever handle, an outside rose, an outside rose liner, and an outside spindle, the outside lever handle having a rectilinear section for manual operation, two engaging posts extending from said outside rose liner;
• a latch mechanism including a housing and a latch bolt, said housing including two positioning holes, said latch bolt being operably connected to said inside lever handle and said outside lever handle such that rotation of either one of said inside lever handle and said outside lever handle causes retraction of said latch bolt into said housing from an extended position;
• a reinforcing plate including two pegs respectively extending through said positioning holes of said housing, said reinforcing plate further including a central hole through which said outside spindle extends, said reinforcing plate further including a pair of slots through which said engaging posts extend, wherein said pair of slots are spaced from the pegs by an acute angle;
• and
• two fasteners extended through said inside rose liner and engaged with said engaging posts;
• when the latch bolt being in the extended position, the rectilinear section of each of said inside lever handle and said outside lever handle being located in a position corresponding to the acute angle with a horizontal axis.