Threaded bottle lid

A lid for closing the end of a wide mouth container having an exterior helical thread of standard design on the exterior of the mouth, said cap having a sealing disc abuttable with the end of the mouth when said cap is in a closure position, said cap having a skirt depending from the periphery of said disc and lying generally parallel to the exterior of the mouth for surrounding same, said skirt having a helical thread form projecting from the inner wall thereof engagable with the thread on the container mouth for obtaining axial movement between said cap and container responsive to relative rotation therebetween, said thread form having a generally inwardly elongated trapezoidal cross-sectional configuration with a base contiguous with said inner wall, a tip extending inwardly to a predetermined clearance with the container, and a pair of side walls converging in the direction of said tip and lying obliquely with respect to said inner wall, said thread form being tilted in the direction of said disc and formed of a flexible material, said inward extension of said thread form being sufficient to cause said thread form to be deflected away from said disc by engagement with the container mouth thread into wedging contact with the root of the container mouth thread when said lid is threaded on the container.