a plastic unitary molded child - resistant , snap - on , tampered - evident closure includes an upper cap portion having internal spaced ribs disposed for cooperation with the upper annular collar on the neck portion of a container , only one rib being sized to pass through the gap of the upper annular collar , and the upper cap portion having an indication indicating the location of the one rib ; a lower skirt portion connected to the upper cap portion and having an inside diameter close to the outside diameter of the upper cap portion ; weakened intermediate portions circumferentially formed about the closure at the connection between the lower skirt portion and upper cap portion ; the upper cap portion including about its circumference a plurality of vertically extending intermittently spaced grooves extending down to the weakened intermediate portions ; a plurality of corresponding openings which separate the weakened intermediate portions and extend through the connection between the upper cap portion and lower skirt portion ; radially inwardly directed ribs located on the interior surface of the lower skirt portion for locking engagement with the annular collar of the container , the ribs being longitudinally aligned with the grooves on the upper cap portion , vertically spaced from the upper end of the lower skirt portion and lockingly engaging the lower annular collar of the container at an engagement portion on the lower annular wall thereof , inwardly spaced from the outer peripheral wall of the lower annular collar when the closure is assembled with the container .