Abstract: A set of injection mold sections are supported and secured to parallel spaced platens of an injection molding press by quick-change locking couplers including a plurality of projecting knobs or studs on each mold section. The studs are received within corresponding cylinders each having a tapered seat which engages a mating surface on the stud. Each cylinder also supports circumferentially spaced balls movable between locked positions engaging enlarged head portions of the studs and retracted released positions in response to axial movement of a spring biased piston within a housing. The pistons are moved to released positions in response to pressurized air supplied simultaneously to the housings. The locking couplers may be recessed within an adapter plate disposed between a mold section and the supporting platen, and the adapter plate has a pattern of threaded holes for mounting a conventional mold section.