The Copper J in purple is a modern attractor nymph in a color trout see well underwater. Purple offers visibility with a buggy, natural read that works in both clear and stained water.
Fish it as a searching nymph in riffles and runs. Size #16 is a versatile middle size for attractor nymphing through the season. Mayfly nymphs are on the trout menu nearly every day of the season, so a pattern like this earns a permanent place in your nymph box.