The MF-846 vent barb assembly can be used in place of the standard MF-841 cap and duckbill valve found on Forespar Marelon Vented Loops. This option enables valveless venting, without the liability of a duckbill valve possibly fouling. Venting can be to the outside of the hull via a 1/4"ID hose, or by simply running the hose vertically above any possible water level.