I believe you are referring to one of these:
This one is actually an 11-piece. But same basic stuff.
I've used & lost quite a few of these over the years.
According to the specs:
Includes Nut driver 1/4 inch / Nut driver 3/16 inch
Which sounds about right. I was sure one was 1/4". And I was sure they were US sizes rather than metric sizes. The ...