Entertech water guns were water guns that had a special feature: battery-power. One would load the necessary sized batteries into the water gun, fill the removable water-clip, and pull the trigger. The batteries would allow the gun to automatically fire in intervals, squirting water quite far every few seconds.
There were several models made, a few which were based (and marketed with the franchise name) after the "Rambo" films. I distinctly remember a pistol, an AK-47, a small machine gun, and a bazooka. Later on, there was another set whereby you would use a base pump to fill up black-colored water balloons. These toys were all realistically molded and probably was a big hazard if improperly used in public.