The only air filter system you will ever need for your PHBH 26, 28, or 30mm carb.

Also fits Dellorto VHSB and Mikuni carbs (may need a slight mod to the rubber boot)

Triple layered micro air filter, easily cleanable and washable and re-usable.

Only measures 38mm in depth from front to back, the shortest air filter on the market so fits under your panels easily without cutting any bodywork.

Kit comprises of;

Advantages

This requires the screw on bellmouth to fit.

https://www.ebay.co.uk/itm/Air-Filter-tea-strainer-type-fits-PHBH-Dellorto-MB-inc-bellmouth-Lambretta/192778190873?hash=item2ce279c019:g:gYcAAOSwuZVcLOgk