[QUOTE=sebmex;2130876]a-grade is a good guaranty isn’t it ??[/QUOTE]
The only A-Grade dual layer media is Verbatim. Everything else is B-grade or lower.
And for the record, you’re wasting your time trying to burn those in a DW1640. The BenQ DW1640 only works consistently well with Verbatim DL media. Everything else is hit and miss. You’re going to end up throwing your money down the toilet and just making a bunch of coasters. Stop now, and try to find a deal on some Verbatim-brand DL media. Please.