From looking into this issue of over size rings and pistons I was confused with the way the parts get advertised but for those who don’t understand here it is:
1st oversize- +0.5mm or +0.020″
2nd oversize-+1.0mm or +0.040″
It is simply an imperial conversion by the Americans from the Japanese metric sizes. Sadly for Philpass I only have 1mm oversize
