Type II sensory fiber (group Aβ) is a type of sensory fiber, the second of the two main groups of stretch receptors. They are non-adapting, meaning that they keep responding even when the muscle has stopped changing its length. They are the second most highly myelinated fibers in the body.
Their firing rate is directly related to the muscle's instantaneous length, or position. This information would indicate the position of one's leg once it has stopped moving.