Stretch Flex is a very strong and durable elastic material from Rainy's Flies. You can use it to tie a variety of flies, including worms, scuds, nymphs, stoneflies, and more. It comes in a variety of colors, sizes, and it is also semi-translucent.
You can use the semi-translucent material to your advantage by planning to use various materials underneath it to acquire different effects. For instance, try using wraps of Flashabou and you will see a neat effect after wrapping the Stretch Flex over it.
When trying to achieve a segmented body, it is best to wrap the Stretch Flex over itself and it's a good idea to make those wraps lie into the center of the last wrap. While wrapping the Flex, pull to stretch it slightly while you wrap. Another tip is before you begin tying the Stretch Flex in, you can make a diagonal cut with your scissors to provide a good starting point when tying the Flex in.