There are slight differences in the standards applied .
Basically ISO Grade P0 is approximately equal to ABEC 1 , ISO P6 approximates ABEC 3 , ISO P5 approximates ABEC 5 , ISO P4 approximates ABEC 7 and ISO P2 approximates ABEC 9 .
There are slight differences in the standards applied , but basically ISO Grade P0 is approximately equal to ABEC 1 , ISO P6 approximates ABEC 3 , ISO P5 approximates ABEC 5 , ISO P4 approximates ABEC 7 and ISO P2 approximates ABEC 9 .