Something that was totally non-obvious to me from Brackett's web site is that the web site only list the filter elements / brackets for which they have an STC. You just have to know about the ones that require one-time approval. But when I called for the filter for my 14-19-3, they had the right filter in stock, with dirt-cheap shipping costs. If I recall correctly, they just sent a bill with the filters rather than wait for my check. Not often that happens anymore.