This is 4x brand new caliper pistons.
part number 516212.
48mm diameter,
29mm deep.
Fits Type 14 calipers :
Spitfire III, IV and 1500 (1967 onwards)
Herald 1200, from GA229455 and 13/60
I also sell the matching seal kit, please see my other items along with many other parts to keep your classic car on the road.