Will Im getting some answers sudco got back to me this is what they emailed me. The 0-0 is the size. Between 0-0 and P-6 there are many sizes. O-2, O-4, O-5, O-6, O-8, P-0, P-2, P-4, P-5 and finally P-6. The O-0 hole down the middle is 2.600mm and the P-6 is 2.780, so if O-0 and P-6 were both...