There is provided a wristband for attaching to a computer device. The wristband includes a first end configured to attach to a first side of the computer device, a second end configured to attach to a second side of the computer device, a battery, a battery connection interface configured to connect to a battery port of the computer device for providing power from the battery to the computer device, and a charging port configured to connect to an interface of an external power source to receive power from the external power source for charging the battery.