The BGM PRO Lambretta air filter is the ultimate replacement for all standardish Lambretta paper filter elements used with the original air box.
 
Thanks to the fine stainless steel mesh the bgm PRO filter gives a very good filtration. The air flow is significantly higher as on the standard item giving power advantages.
 
The filtration can be optimized further with using air filter oil. But for all street applications the filtration is perfect as it is.
 
Next big point on the bgm item is that it can be cleaned with brake cleaner or similar fluids. Much better than replacing the standard filter every 6,000km when it is clogged by dust.
 
Upshot: Higher airflow so more power, Perfect filtration, Washable.
 
PLEASE NOTE: You should be prepared to up-jet your carb because of the better airflow.