This 12cm fan guard look like a fancy speaker cover.
Is made of a very sturdy, 0.8 mm powder coated steel. It is very hard to bend by hand [as in not flexible]
Best fixed by screws but rubber ones would work.
Why it is better than a grille or a plastic / PVC filter? A grill have no dust protection whatsoever, plastic filters reduces your intake air massively and they get clogged in no time.. furthermore the thin, plastic ones, are very flexible and tend to get pulled into the fan impeller, producing a scratching noise.
This metal PC fan guard is a great compromise not to mention the finished look!
Open area 40%