SuperFly and Perfect Hatch Threads
The SuperFly 3/0, 6/0, and 8/0 are all much thinner other brands of thread labeled as these sizes. They are very strong for their very thin diameters with no noticeable stretch.
For Perfect Hatch I only have Black 3/0, 6/0 8/0 .
SuperFly comes is some great colors, 3/0, 8/0, 6/0 for most colors.