Benecchi Tying Thread is an excellent tying thread in all the right colors for all types of flies.

It is available in 2 thicknesses 10/0 and 12/0. 10/0 is the thickest and 12/0 the thinnest.

12/0 is excellent for dry flies, nymphs, wet flies, etc.

10/0 is a really nice all-round thickness for most things.