"The Mercury RS-2 fishes best when you begin to see a mayfly hatch in progress. When trout push up into the shallow riffles, transition areas, or mid–channel shelves, this fly is deadly. It hammers fish keying on Baetis or pale morning duns." - Pat Dorsey
I picked up this fly before heading to the Colorado River a few weeks ago. I was referred to get this by Jack at the shop. 2 days later I'm pulling in a 25 inch rainbow and it hit the RS2 size 18. I was ecstatic! Would not have been able to bring my personal best in if it wasn't for having this fly on the line per Jack's suggestion!