This is Directron's black 80mm steel mesh/filter. I did a mini-review about these. Here's the link. I wrote the information regarding the grills and my new window fans. But here, I will add the front panel blowholes.

Thinking that these grills would help give my front intakes more airflow, I cut out the perforated part of my case front panel. Since the corner holes already line up to fit an 80mm fan, I kept the corner holes so i can mount the grills there. To protect my beautiful case' brushed aluminum finish, I covered it with some masking tape (those sign makers transfer tape are so cool. covers a big area pretty well). Here's what I ended up with. This is after filing the edges to smoothen them.