This is a full OEM Glock factory kit but is compatible with any aftermarket frame kit as well (brownells, polymer 80, shadow systems and others). Mates up with gen 3 frames but will also function with a gen 4 if you have the right recoil spring or adapter. The item "Glock 19 19C Gen 3 OEM Complete Upper Slide Assembly Polymer 80 RARE Parts Kit" is in sale since Sunday, February 28, 2021. This item is in the category "Sporting Goods\Hunting\Gun Parts\Pistol".The seller is "thatglockguy" and is located in Broken Arrow, Oklahoma. This item can be shipped to United States.