the standard propagation tank board...

I was about to start fragging my corals until i noticed that i need a plastic board to hold them up (its a small nanocube that im converting to a propagation tank, it doesn't have a "super" stronger light but its enough if the "groud level" is raised). From all the pictures i've seen in propagastion tanks in tanks im wondering whats type of plastic board is that? It's white with round 14 in. holes that are boxes throughout it...
just wondering
 
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