Filter cups too small

[Saltywaters]

I purchased some 4” filter cups to try using instead of filter socks and not too happy.
They are loose, and most water goes under the lip. They do not snap in like my filter socks.
Anyone use filter sock cups with a marine biosystem sump kit that can recommend where to buy some cups?

 

[ryanjohn1]

Brs had a plastic ring deal that went between cup and where it sits.

 

[Reef.]

I purchased some 4” filter cups to try using instead of filter socks and not too happy.
They are loose, and most water goes under the lip. They do not snap in like my filter socks.
Anyone use filter sock cups with a marine biosystem sump kit that can recommend where to buy some cups?

what tank is it or sump hole diameter.