help with the baffels

hello, i have now decided to finally get round to building something and have chose to build 2 tda style mt121's. but wanted to make sure i know exactly how to do everything before i start. i have worked out pretty much everything apart from if you look at the simplified plan it shows the 12mm thick side of the baffels. but one side is 360 and the other is 356.im guessing this is because of the shape of the box it has to get smaller. and it this achieved by doing a mitre cut? any help is massively appreciated. thanks

and is that on both baffels? thanks for the help

have you seen a single 15" plan for this? I'm trying to avoid running a kick bin and 12's won't go down low enough..

15" section for that say 300 to 120 will your horn be about to go down to 300hz??