B18B piston size

[a.pezzuto]

I need to replace the piston rings on my B18B2 engine, after taking off the head, i noticed that the pistons where marked with "PR4 0.8" i was just wondering if this means the pistons are over sized, if so, would it be 0.8mm oversize? and also will it be a problem getting oversized piston rings?

[oopoc]

If the head is off measure the pistons