Antifreeze/Coolant - what does B in front of part number mean?

[Graham]

Last time my E320 was flushed at dealer, they used coolant part # Q-1-03-0002 .

I bought one jug later from local dealer for top ups. It is part # BQ-1-03-0002 and spec 325.1.

Anyone know what the B signifies?

The coolant is to MB spec 325.1 - doesn't show up on Bevo. (MB gave changed their coolants, but still use same spec numbers)

What I also don't know, is whether this is 100% or a 50/50 mix. I seem to recall parts guying saying it was 50/50, but it doesn't say that anywhere. To add to confusion, my invoice says Q-1-03-0002.

By the way, this is the older coolant as used on our 98 E320 and is same spec as Zerex G05. Planning on doing flush and would like to use this jug if I can.

Some pics: