Hi Noel...assuming you are talking of a tank mounted Vokes I don't think these are available. The originals filter elements were 10 felt tubes, clipped to the manifold at the back end and clamped at the front.
I went and bought some felt and sowed up the tubes for mine....Ian
These Vokes filters are noisy things and riding around with it without any of these tube fitted doesn't help I can tell you that. During our trip to the South of France years ago I removed the tube between the filter and the carburettor as I just couldn't stand the noise any more after a while. Fitting these tubes would surely have reduce that noise to a better level.
I found having some felts fitted quietened things down a bit...but not much. However, I like the sound the filter makes, even on a long run. I guess I must be tougher than Henk ..or my hearing is worse...Eh?...Ian