Polini's airbox for the smallframe carburetors is actually nothing more than a box: There is no filter element here, the airbox only serves to dampen noise.
Unfortunately, Polini has now cast the previously removable white sleeves into the body. This means that the only way to adjust the air volume is to drill out the pre-drilled holes. If this makes the intake noise too loud, a suitable tube (e.g. from a DIY store/model shop) can be inserted into the hole(s). This breaks up the sound and still allows sufficient air to pass through. The version for the 24/25 mm carburetors already has fully open holes.
Gives the engine enough air and dampens the intake noise.