Crafted to be the best sounding, full featured, portable Bluetooth speaker in its class, The Onyx studio 4 offers two device connections, 8 hours of playtime and Harman Kardon connect+, which allows you to connect 100+ speakers with the same feature with the touch of a button. Rounding out the Onyx studio 4 offerings is a built-in microphone with voice logic, echo and noise cancellation for crystal-clear conferencing over the speaker.