Sundown SA-12 mounting screws location

[Golitan11]

I have seen people screwing it over the gasket, with and without washers, and I have seen others screwing it in the gasket (I don't know where actually lol). I just wanna know what is the proper place to screw them down since most screw heads barely fit in those holes. Thanks.

P.S. Now, I have #10 2" stainless steel screws (flat head) and #6 1"5/8 coarse drywall screws. Since I have a double baffle enclosure, I don't know which one would be better too.

[DylanBunch]

the gasket is rubber so the screw head will go through, itll stretch. Mine does on my x 18