Needed for a rear caliper it's about 43mm diameter and wind-in-able!

I got new pistons for the front calipers from bigred, http://www.biggred.co.uk/ not expensive.

Cheers

Ian

I have a pair of sierra rear calipers (piston half) that were fitted with new gaiters and piston seals a year ago. One of them leaks a bit through the handbrake lever seal that I didn't replace. The castings are rusty but they are surplus to requirements if you are interested.

Well I only need the one piston and big red will do it for £9 so I'll go with that I think as I don't need whole new calipers but thanks all.