The specifications for pipe threads are regulated in ISO 228-1.

For the MAG-VIEW means the following:
Example G 3/8 is the Nominal size of the thread

Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP; originally also known as British Standard Pipe Fitting thread), which have a constant diameter; denoted by the letter G.

For male threads, there are a total of 2 tolerance classes, A and B.
For female threads, there is only one tolerance class, and no specification is necessary here.
All MAG-VIEW has a B Tolerance class