On the left ear cup is the switch that will turn on the ANC and a 3.5 mm input jack for when the battery dies out. (soundguys.com)
On the bottom of the left earcup, you'll find a 3.5 mm input jack for the provided cable, along with power and ambient audio adjustment buttons outfitted with two differently sized plastic nubs on each button to make them easy to distinguish while the headphones are on your head. (digitaltrends.com)
Essentially Chromecast Audio makes any amplified speaker with a 3.5 mm input jack a wireless speaker, which happens to be almost every Bluetooth speaker and powered computer speakers. (ecoustics.com)