Customer Support

Find answers to the most frequently asked questions by our users.

this is MK3 user manual

-Currently, the SOS button is available only in Android operating systems after installing a separate application (MK3).

- The SOS button operates only after it is pressed 3 consecutive times to prevent a malfunction.

- You can use an earphone by connecting a 3.5mm ear jack. However, the mic input of the earphone is not supported.

-It may be necessary to adjust the Bluetooth volume depending on the smartphone     model. Adjust the smartphone volume with the MK3 volume set at a high level.

- For certain models with an Android version 8.0 (Oreo) or higher, go to ‘Settings’-> ‘Device information’-> ‘Software information’, and then click ‘Build number’ a number of times to open the Developer options. Then, change the 'Disable absolute volume’ option.


- MK3 is a device which controls Zello, a transceiver application for smartphones, remotely via Bluetooth.

- It enables multilateral communication without distance limitation using the data communication methods (3G, 4G, Wi-Fi, etc.) of mobile phones.

- MK3 is a multi-functional device for outdoor use, which offers Zello wireless communication, Bluetooth speakers, hands-free use, LED flash light, emergency messaging (location information transmission), and a touch pen.

- Check if data communication is enabled in the smartphone.

- Update Zello to the latest version.

- Pair the device with a smartphone according to its operating system (android, iOS)

  (MK3 provides 2 pairing modes for android and iOS.)

- Exit the Zello app and restart it, then try again.

- The PPT key does not work in Zello in an environment where data communication is disabled.


- Refer to the Detail Instructions and set the Zello options correctly.

Android : Apply audio mode only when a message is sent or played

iOS : Mix with other audio