Air filter insert required.

Hi there

I want to replace the air filter insert currently used on my S3 landy, but this is proving harder to do than I previously thought.

There is a couple of pictures here:

Basically, I need the sponge/mesh insert that fits on the top of the carb. Its dimensions are:

External diameter: 5 6/16 inches (135mm), internal diameter 3 11/16 inches (95mm) and height 2 1/16 inches (52mm) - all measurements are approx!

I have tried the local motoring shops, to no avail. If anyone knows of a supplier of the filter, I would be grateful.

Thanks in advance.

Kevin