The ones I've seen are flat screens sandwiched between aluminum plates with very small dimension filter screens. When an old style canister filter element is disassembled, there are many square feet of available surface area. I can't imagine the small mesh screens running very far without clogging and becoming worse than useless.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!