Chromecast Audio is a variation of the second-generation Chromecast designed for use with audio streaming apps. Chromecast Audio features a 3.5 millimeter audio jack/mini-TOSLINK socket, allowing the device to be attached to speakers and home audio systems.[26] One side of the device is inscribed with circular grooves, resembling those of a vinyl record.[27] A December 2015 update introduced support for high-resolution audio (24-bit/96 kHz) and multi-room playback; users can simultaneously play audio across multiple Chromecast Audio devices in different locations by grouping them together using the Google Home mobile app.[28] The feature made Chromecast Audio a low-cost alternative to Sonos' multiple-room music systems.[29]