Audio-Technica ATH-CKS50TW Noise-Canceling True Wireless In-Ear Headphones (Black) - Manual (Page 18)

Power supply ON/OFF
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The power will turn off automatically.
Press and hold (for about 4 seconds) the multifunction buttons to turn off the power manually (while
pressing and holding the multifunction buttons, you will hear a confirmation sound once after about one
second, but keep pressing and holding until the power is turned off).