The problem starts when you have holes or hole making tools for PG and go metric. A 47 mm punch is no good when the glands are either M40 (40 mm) or M50 (50 mm)...

More annoying is the fact that an M40 from one manufacturer hasn't the same inner diameter as an M40 from another manufacturer!

Still, the metric is better than the PG (fewer sizes to cover the same range) but currently this all seems in limbo... [Linked Image]