Shure SE310A-k Sound Isolating Earphones (Black) Sound isolation technology blocks background noise for an ultimate listening experience Sound signature provides a unique acoustic sound to address specific listening preferences using Hi-Definition MicroSpeakers plus Tuned BassPorts Deluxe fit kit includes multiple sleeves to choose from for the most comfortable in-ear fit Modular design allows for the use of variable cable lengths and the ability to add optional in-line accessories such as the Push-To-Hear accessory Frequency range of 22Hz-19kHz