HAs anyone ever heard of rocker bars, or limb rockers on a compound bow?

If so where are they located? Are they hard to find?

Some manufacturers use these to anchor the limbs in the limb pocket. To see if your bow has them, remove the limb. Martin has them on their bows - with a particularly good design, in my opinion. The rocker is a round item that will fit into a depression in the limb pocket and mate with a depression in the limb. Some are shape like balls, others like rollers.

I much prefer limb rockers over pivoting limb pockets and especially over limb pockets that rely on the pocket sides and the limb bolt to anchor the limb.

They need a little lubrication to prevent squeeks, but other than that, there isn't any maintenance to perform on them. They are a simple concept that allow a manufacturer to make an inexpensive, yet very effective limb pocket.