This is my variation of the original created by Jim Estes in the 1990s. Imitating small bait fish, caddis larva, cased caddis, crane fly larvae, grub, caterpillar, worm and many many more at the trout love to eat. My favorite way to use the mop fly is as the attractor on a double dropper setup under a strike indicator. It works great by itself under an indicator. 4X to 6X tapered leader and tippet are excellent choices.