This is the upgraded two stage filter with the built in pressure relief valve on the bottom that goes in the Provent 200. Unless you have the \"IV\" upgraded inner cap, this updated filter will not fit the original design that has the relief valve in the outer cap. This is an excellent filter with two different filter elements made of two different materials. It also has a coalescing pre-filtering screen inside that turns the oil mist in the air into larger droplets so they are easier and more efficient for the two stage filter to trap. While this filter is rated above 90% efficient, there is room inside to place a small wad of stainless steel wool to further raise the efficiency by acting as another pre-filtering coalescing screen.