I don't know what they're called technically but that's the best description I could think of. or to put it in another way, it's a metal sheet with alot of nicely spaced and aligned holes all throughout the sheet. it looks similar small speaker grilles like the ones on tweeters, etc. I'm not familiar with their available thickness and hole diameters so I guess suggestions as to where they could be sourced out would do just fine and I'll just help my self to whatever they have in stock and see if they're the ones I need. tia.