This is a remix bit holder to keep 8 nut bits from 5 mm to 13 mm. It helps carry the bits in tight form as original casing was only for laying bits down. This block is a compact but still handy with removing nuts and thanks to the pegs it holds the bits even upside down.
The nuts in the set are 5, 6, 7, 8, 9, 10, 11, 13 mm.