Overview Reviews Product Description J21 Adjustable Downstream Injector 2.1 MM 2.7 - 4.9 G.P.M. 3200 PSI 0-15% Injection rate 200°F Temp. 3/8'' MPT inlet & outlet Product Videos Custom Field Product Reviews Write a Review Write a Review × GP 249 - Adjustable Downstream Injector, J21, 2.7 to 4.9 GPM Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Review Subject * Comments *