Bitspower G1/4" Carbon Black AIR-Exhaust Fitting

I imagine this would be most useful when initially filling a long loop and bleeding bubbles out of your lines. If you don't vent the air and you first try to run water into the pump, it's tricky. Bleeding air out of the loop halfway through or at multiple points can make life a lot easier and the process much faster than forcing the pump to push the air all the way back into the reservoir, especially if you like to do maintenance on your rig and have to refill at regular intervals.