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.