The Marquest Nitrogen Gun Filter is used in our Model ANG (Aquis Nitrgen Guns). The replacement filter is a 0.8-micron syringe style filter made of PVDF (polyvinylidene fluoride) material with a diameter of 25mm. This filter is specifically designed to be used inside the gun cap of the AQUIS Nitrogen Spray/Drying Gun for the purpose of dispensing nitrogen or other inert gases.