Ultra Thread 140 is a versatile saltwater fly-tying thread. It has the perfect amount of stretch to help tension down on your materials to help make for more durable flies.

The Ultra Thread 140 wraps smooth, doesn't fray easily, and lays flat. As a result, it is becoming increasingly popular for saltwater flies. For example, its equivalent diameter in Danville is 6/0, a size most often used with trout flies. So you get a thin diameter with a breaking strength of around 2 pounds. Ultra Thread was designed for fly tying and isn't just a re-purposed thread from some other application.

Perhaps bump up to the Ultra 210 (a heavier thread) if you're tying the biggest saltwater patterns.