Binks Model 21 automatic guns feature nickel-plated brass air caps and bodies that will withstand years of use under the toughest conditions. The spray guns contain tungsten carbide fluid nozzles and needles for use with abrasive materials. The Model 21 spray guns are internal mix spray guns used in line striping applications. The guns are designed to deal with rough environments both inside and outside the spray gun. The internal mix air cap keeps the spray pattern precise while the quick actuating air valve ensures materials is only sprayed where and when you want it. The Model 21 Automatic Guns are available in three different models; Model 21, Model 21V and Model 21M.