Air Filter

Hi,
Can anyone recommend a good foam-type air filter that will fit straight on to the mouth of a 30MM Dellorto? Not the type fitted with the rubber elbow.
And also would it fit on to the threads or would the plastic bell mouth have to be fitted?
Thanks in advance.
Can anyone recommend a good foam-type air filter that will fit straight on to the mouth of a 30MM Dellorto? Not the type fitted with the rubber elbow.
And also would it fit on to the threads or would the plastic bell mouth have to be fitted?
Thanks in advance.