Syahar1975, making a guess here but, I'd say the bolt is dual-certified SA-193 B7 & SA-320 L7. Both the same nominal composition, SA-320 is impact tested. Depending on your Code of Construction, SA-193 B7 may have a higher max temperature limit. There may be other differences.

You would likely need to confirm the dual certification, review the two specifications, your Code of Construction, if any, and assure yourself the bolting is suitable for your application.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

Syahar1975,
As an engineer you should compare the actual material/chemical properties of the actual bolt and check to see if it meets your criteria instead of asking others to do your job.

The dual certified bolt has been tested to meet the requirements of both the B7 and L7 specifications. It isn't that one is 'better' than the other, just that it has been tested to meet both specs. If you need parts that meet both specs in the same application, go for the dual certified, if you don't need both specs, then just get one or the other certifications.