Abstract: A tamperproof push-on type integral synthetic plastic closure cap for an externally beaded container neck, the cap comprising a body having a depending side wall, a rim on the lower end of the wall having an inwardly projecting locking rib adapted to coact with a bead on the container neck, a circumferential weakened region in the wall disposed above the rim, and a tab projecting outwardly from the rim, the wall having a slotted region adjacent the inner end of the tab and there being a weakened connecting region formed by a notch between the rim and the inner corner of the tab so that twisting the tab will break the rim at the notched region and enable the rim to be detached from the side wall along the circumferential region by outward pull on the tab.