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Bottle Top Filter Homebrew Question

I have a Whatman Zap Cap bottle top filter which I am trying to use with a Hybex glass media bottle. The Zap Cap filter is supposed to work with 33-45mm media bottles, which this Hybex is (45mm). My question is, how does one go about attaching the filter to the bottle. They don’t screw together, and the filter seems to just loosely sit on the top of the bottle. When I attempt to apply pressure with the hand pump, it doesn’t really do anything. How is a seal formed between the filter and the media bottle?