What are the holes in the top of my 1993 Toyota Corolla's trunk for?

I have a 1993 Toyota Corolla, and I am installing a new sound system. The Car Fit guide at Best Buy tells me that I need 6 1/2" speakers for the trunk, which will fit the two outside holes in the the top of the trunk, but there are two larger holes as well. I don't know what they are for, and I'd like to be able to fit larger speakers in there. Anybody know what they're for?What are the holes in the top of my 1993 Toyota Corolla's trunk for?i have seen this twice in one car there were brackets there to hold the 6 1/2's , the kid didn't have the braket so he ran 2 5x6's in there , the other time there were brackets dut the dude took them out and put in 6x9's so depends on what you wanna do , if you can make a board the 4 6x9's could be an option .

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