Some widespread piano tuning resources: From leading to bottom: a tuning lever, a felt mute, a rubber mute, a felt temperament strip (still left), as well as a Papps mute. Prevalent resources for tuning pianos contain the tuning lever or "hammer", a variety of mutes, in addition to a tuning https://jeffreybijid.onesmablog.com/top-piano-tuning-secrets-71312940