Thank you for your support to TinyDeal.
The battery is in-built, so it is hard to check and there is no information on this from our manufacturer. While we have to say that many buyers bought it and they loved it, too. So there is no need to worry about the voltage.
The dimension of the item you mentioned is : 180 * 90 * *45 * mm/ 7.1 * 3.5 * 1.8 inches as we stated on the site, this is the result after our checking.
Any other questions please feel free to contact us on https://help.tinydeal.com/contact-us. And we would answer you within 24 hours.
Have a nice day!