Fed up of your calliper pistons seizing in after leaving your Lambretta stood for a few months or years?
 
With all the road grunge, disc brakes and particularly the pistons, tend to take the brunt of it causing them to stick and eventually rust.  New pistons and seals should cure the problem.
 
Suitable for ScootRS and Sterling/SPAQ type Nissin and Taiwanese copy callipers.  These may fit other types but you would have to check.