Abstract: A thermo-formed container closure having a breakaway ring including at least inwardly extending tab on the ring for engaging a lug on the container to prevent the ring from rotating as the closure top is unthreaded in which an annular flange joining the breakaway ring to the closure skirt wall is cut, except at a plurality of retaining bridges, with each of the bridges being of generally trapezoid shape and having a minimum area where the flange is attached to the closure skirt wall and a maximum area at the breakaway ring portion, to enhance the breakaway action as the ring is prevented from rotating.

Abstract: A container closure which is thermoformed from a sheet of two different materials which are bonded together, the material forming the inside of the closure being relatively soft to serve as a liner.

Abstract: A tamper-proof closure for a container having a member projecting from its neck, in which the closure is thermoformed with a skirt wall having a tab which engages the projecting member and which breaks off as the closure is unfastened from the container.