I've lost the rubber grommet that covers the seat post adjuster on my tm02. Does anyone know where to get a replacement in UK?

If someone could measure the grommet and let me know the dimensions (a, b and c in diagram below) it would be really helpful in finding a replacement. I wish I had measured mine before I lost it!




Edit: I've managed to get the measurements now. In case it's any use to anyone else they are: a: 14mm, b: 5mm, c: 10mm.

First question still stands though, anyone know where to get a replacement?!