STX825 Waveguide - Use Gasket?

[DES-1]

Can anyone tell me if a gasket is used between a horn and a driver, or do they just bolt up? Specifically, the STX825 waveguide and a D2? The diagram and parts list I found doesn't show a gasket but the diagram could be a simplification.

I'm starting to gather up the bits and pieces for a build, and I'll likely have more basic questions, some might be rather elementary :confused:

[DES-1]

After unboxing the D2's I learned they have an integral gasket, so it was on to mounting the drivers and horn:

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