For iPhone 5S Replacement External Side Button Power Switch+ Volume Switch + Mute Switch Set
The mute switch sets the iPhone 5 in mute mode
You may have encountered things like these:
iPhone dropped on the grond,and side buttons broken or no reponse no matter how hard you push the button
http://www.hytparts.com/000670-for-iphone-5s-replacement-external-side-button-power-switch-volume-switch-mute-switch-set.html