A container closure. The closure comprises a pressure closure assembly and an outer release shell configured to be coupled thereto. The assembly comprises a relief valve and an inner shell having a base wall, a pressure relief slot, and an outer skirt extending away from the base wall and including first and second portions. The release shell includes a first portion having a base wall configured to overlap a portion of the inner shell base wall, and a tab corresponding to the slot of the inner shell. The first portion further includes an outer skirt extending away from the first portion base wall and configured to wrap around the first portion of the outer skirt. The release shell further includes a second portion having a base wall configured to overlap a portion of the inner shell base wall, and an outer skirt extending away from the second portion base wall.