What it is
Hareline’s Plastic Fly Rattle is a small fly-tying rattle insert with a plastic body and metal beads inside. It’s built to make noise in the water and it’s durable, with a stub end that gives you something solid to lash down on the hook shank.
What to tie with it
You use it to add a rattle to a fly by tying it in along the shank as part of the body, or by sliding it inside mylar tubing. It also gets locked in place and protected with an epoxy or UV resin coating, which is a common way to keep the rattle centered and streamline the profile on baitfish-style streamers.
Flies and the fish they're for
Rattle Zonkers are a natural fit for this insert, giving a rabbit-strip streamer extra sound for bass in lakes and rivers, and for trout when they’re willing to chase bigger meals. EP Rattle Flies use the same idea in a baitfish profile and are commonly fished for bass and other predator fish anywhere you’d throw a minnow imitation. More broadly, tyers work rattles like this into general minnow patterns for bass and trout, and that same noisy baitfish concept crosses over well to saltwater predators in stained water.
How it compares
Compared to glass rattlers, plastic rattles are better left uncoated in rough, rocky areas because they’re less delicate, even though glass tends to be louder. If you want maximum sound you lean glass; if you expect your fly to get banged around, the plastic rattle is the tougher choice.