The K&N #2820 is a 3" opening and is straight round with dimensions of 5" by 6-1/2"
I see that you're a senior in HS, and cash has to be hard to come by. That will probably flow enough cfm for a modded SE or stockish SVT.
The big ole K&N #3530 was $45 shipped to my door.
The MAF adapter from Duratech Performance was $27 shipped.
Total = $72
That guy wants $40 plus $12 shipping = $52
Your savings = $20