Many of the smallest sizes are just plain repeating. From 0.6mm to 0.3mm they all read as 0.49mm. So I think I have a good stockpile of what they call "0.5mm". Values above 0.6 appear to be reasonably accurate. I'll keep this set because the pin vise seems like a good deal and it doesn't cost the gas it takes to return it to the UPS store.