The airbox to the PVP carburetor, have on filter inside, and there is a 5 mm. hole in the bottom, so the the water can come out if you drive wet races. The size of the box inside is 150x500 mm. The part number of the airbox is 4032.

This is the filter inside the airbox, the filter have  part number 4033

Inside the airbox is there this fiber ring as you can see on the photo, to give the perfect bellmouth.