ULTRA 70 has a breaking strength of approximately #1 and is recommended for size 14-32 flies
Lies flat less build up on the smallest trout pattern
Great for thread bodied nymphs and midges
70 denier nylon

ULTRA 140 has a breaking strength of approximately #2 and is recommended for size 6-14 flies
A good general purpose thread that is also perfect size for beginners tying trout flies
Makes a wonderful thread for the split thread dubbing technique
140 denier nylon