If your use case requires you to exclusively use either desktop or mobile user agents in the headers it sends to the website then you can use the device_type parameter.
Set device_type=desktop to have the API set a desktop (e.g. iOS, Windows, or Linux) user agent. Note: This is the default behavior. Not setting the parameter will have the same effect.
Set device_type=mobile to have the API set a mobile (e.g. iPhone or Android) user agent.
Note: The device type you set will be overridden if you use keep_headers=true and send your own user agent in the requests header.