An apparatus for use in a hot runner co-injection molding system, comprising: a gate adapter body having at least a pair of nozzle passages (28, 30) formed therein, each of said nozzle passages (28, 30) having a passage outlet (44, 46) in fluid communication with a gate outlet; at least a pair of nozzle assemblies (16, 18) mounted in said adapter body, each said nozzle assembly (16, 18) having an end in fluid communication with a source of liquid extruded material and a nozzle outlet (24, 26) in fluid communication with an associated one of said nozzle passages (28, 30); a valve stem disposed in said adapter body adjacent each of said passage outlets (44, 46), said valve stem being operable to selectively allow material flow from said passage outlets (44, 46) to said gate outlet; and an actuator connected to said valve stem for selectively moving said valve stem to control material flow from said passage outlets (44, 46) to said gate outlet, wherein each of said nozzle passages (28, 30) extends for a short distance within said adapter body to minimize heat transfer between the materials in said nozzle passages (28, 30), wherein said valve stem includes an end seat and an elongated body portion, wherein said end seat cooperates with one of said passage outlets and said elongated body portion cooperates with another of said passage outlets in a first valve position of said valve stem to prohibit material flow from said passage outlets (44, 46) to said gate outlet, characterized in that said valve stem includes reduced diameter intermediate portion having a smaller diameter as the elongated body portion which reduced diameter intermediate portion is provided between the end seat and the elongated body portion, and the first one of said nozzle passages extents into the second one of said nozzle passages (28, 30) along a common axis shared by said nozzle outlet of said first one of said nozzle passages (28, 30). a gate adapter body having at least a pair of nozzle passages (28, 30) formed therein, each of said nozzle passages (28, 30) having a passage outlet (44, 46) in fluid communication with a gate outlet; at least a pair of nozzle assemblies (16, 18) mounted in said adapter body, each said nozzle assembly (16, 18) having an end in fluid communication with a source of liquid extruded material and a nozzle outlet (24, 26) in fluid communication with an associated one of said nozzle passages (28, 30); a valve stem disposed in said adapter body adjacent each of said passage outlets (44, 46), said valve stem being operable to selectively allow material flow from said passage outlets (44, 46) to said gate outlet; and an actuator connected to said valve stem for selectively moving said valve stem to control material flow from said passage outlets (44, 46) to said gate outlet, wherein each of said nozzle passages (28, 30) extends for a short distance within said adapter body to minimize heat transfer between the materials in said nozzle passages (28, 30), wherein said valve stem includes an end seat and an elongated body portion, wherein said end seat cooperates with one of said passage outlets and said elongated body portion cooperates with another of said passage outlets in a first valve position of said valve stem to prohibit material flow from said passage outlets (44, 46) to said gate outlet, characterized in that said valve stem includes reduced diameter intermediate portion having a smaller diameter as the elongated body portion which reduced diameter intermediate portion is provided between the end seat and the elongated body portion, and the first one of said nozzle passages extents into the second one of said nozzle passages (28, 30) along a common axis shared by said nozzle outlet of said first one of said nozzle passages (28, 30).