Closure and package having child-resistant and non-child-resistant modes of operation

A package having child-resistant and non-child-resistant modes of operation, which includes:

• a plastic container having a cylindrical finish with an open end, at least one external thread on said finish, and a manually deflectable release element externally cantilevered from said finish on a side of said at least one thread remote from said open end, and
• a plastic closure that includes:
• a plastic inner shell having an upper end, a skirt with at least one internal thread for engagement with said at least one external thread on said finish, at least one external bead on said skirt and at least one external engagement element on said skirt,
• a plastic outer shell having a skirt externally encircling said skirt of said inner shell, at least one internal bead on said skirt, at least one internal first engagement element on said skirt on a side of said internal bead adjacent to said upper end, at least one internal second engagement element on said skirt on a side of said internal bead remote from said upper end, and at least one third engagement element adjacent to an edge of said skirt remote from said upper end of said inner shell for engagement with said deflectable release element in a child-resistant mode of operation,
• said inner shell being positionable within said outer shell in a non-child-resistant first position with said external bead on said inner shell disposed on a side of said internal bead of said outer shell remote from said upper end, said internal second engagement element on said outer skirt disposed for engagement with said external engagement element and said third engagement element on said skirt of said outer shell spaced from engagement with said release element such that said closure can be unthreaded from said container finish without deflecting said release element, and
• said inner shell being positionable within said outer shell in a child-resistant second position with said external bead on said inner shell disposed on a side of said internal bead of said outer shell proximate to said upper end of said inner shell, said external engagement element on said inner skirt disposed for engagement with said internal first engagement element of said outer skirt, and said third engagement element on said skirt of said outer shell positioned for engagement with said release element such that said closure cannot be unthreaded from said container finish without deflecting said release element out of engagement with said third engagement element.