Air small air filter with a 35mm inlet suitable for pre-65 trials and many Japanese applications as follows:-
BSA / Triumph etc. some Monobloc and pre-Monobloc carburettors.
Honda CB100N, CB125TD, CB400F, MBX/MTX50/80
Kawasaki AE80 (81-83), AR80, KH250
DT80MX (81-83), RD88 LC (82), RD125/200 (75-81)
The filter is approximately 62mm at it's widest point tapering down to approximately 51mm. The overall length is 70mm from back to front. The end caps of the filter have a nice deep chrome finish.
These filters should always be oiled before use for maximum filtration efficiency. K&N Filter Oil is available from this site