Abstract: The disclosure relates to synthetic resinous container closures having frustoconical sealing surfaces which cooperate with corresponding sealing surfaces on a container finish to effect a gas-type seal. In one embodiment, the closure is particularly suited for use in sealing containers having pressurized contents such as carbonated drinks and the like. In a second embodiment, the closure is of threaded type enabling the reclosing and sealing of the engaged container after an initial opening. This embodiment including a separable tamper-indicating ring. In a third embodiment, the closure is adapted to be used in conjunction with an aerosol dispenser to exclude ambient moisture from the area of the dispensing nozzle prior to first use, and to form a second seal after the closure has been removed for first usage.