I have some material I got from a kit called Poly Yarn. I use it as wings for spinners and as a substitute wing on various dry patterns like the Wulfs. It is real easy to handle and I find it useful for practicing the different winging techniques. I have two questions about it:

1) Is this the same as antron yarn ot Z-lon?

2) Reading in the Orvis Fly-Tying guide, the author states under a section on synthetic wings, "stiffer wings made from these (synthetics) have to be perfectly matched or they will twist your leader into a Slinky." What does he mean by this? I don't think he is talking about synthetic yarns, but there is a picture of a spinner tied with what looks like poly yarn.