The Red Tail Stimulator is perfect when your standard dries aren't getting strikes. This fly pattern is huge and bushy which helps to provoke the fish into striking it.
The Red Tail Stimulator floats really well, even after 30 minutes or so of use. Due to its large size, we like to tie a smaller dry fly behind it, like a size 16 caddis or Adams.
Having a decent variety of stimulators is key to your success as a fly fishing angler.