A couple years back, I wrote about a tube fly pattern for salmon that had ‘flippers’ as fluttering attractors. I recently came upon a similar attractor concept for a pattern tied by Brian Størup called a Potty Pig. Both patterns utilize a hackle stem with most of the barbs stripped away and leaving a tip that with resistance must flutter about. This is a leaner appearance than many steelhead/tube patterns. This is worth a look see.
Note the badger hackle tips (tails) extending back. In the pattern below the shorter ‘flipper’ would provide the same fluttering attraction and is from a hackle tip trimmed.