Do-All Outdoors - Boost Series C Ear Plugs, 4 Channel, One Size NEED-BASED ADJUSTMENTS: can be used as an open fit device(when enhancement is all that is needed) or a closed fit device with one of six different tips(when enhancement and protection are both needed) FEELS LIKE A CUSTOM FIT: without the hassle or cost of getting a custom fit SECURE: by locking into the concha bowl of your ear, device remains secure even during physical activity FOUR VOLUME SETTINGS: in order to tailor the sounds to specific needs and preferences CONVENIENT: easily portable due to its small size