STD size low drag slipper type pistons with a minimum 8.8:1 compression ratio but on some Metro versions it was higher.
Current pistons differ from the 60s originals, improved with a "low drag" slipper skirt design and a shorter lighter wrist pin.
Wrist pin height to crown is 1.4689", crown has 8cc dish, and they have two 1.5mm compression rings and a 4mm oil ring.
From the top ring to the crown these measure about 7mm and the high compession P21253 piston have 10mm gap from top ring groove to crown.
Ringset is
R35960-00.
Sold singly,4 per engine required
AE Hepolite is now owned by Federal Mogul and trademarked "Nural".
Now Nural stamped 87-521700-00