Whether the mottled tan or dark brown is better remains an ongoing guide debate. Both work exceptionally well. Our guess is trout mistake these for Skwalla nymphs but they also resemble small crawfish. The tung head drops fast and the jig hook affords long dropper tippets under a dry (3’ not uncommon) or short leash nymphing without extra split shot and minimal snags. Fish ‘em hey diddle diddle, right down the middle. This is a go to bug even when fishing is challenging.