Rabbit "Listening Only" Classic Ear Hook is made of soft flexible rubber. In addition to comfort, the "outer" earpiece feature allows the unit to be worn by multiple users without compromising hygiene. The comfortable 15mm speaker rests securely in your ear, producing a rich, full, natural sound that can be heard only by the user wearing the earpiece. The speaker rotates to affix to either ear and moves up and down for a custom fit.