Abstract: The present invention relates to a tracking system comprising a tracking device. The tracking device in the form of a barrel-shaped unit contains geo-location circuitry and communications circuitry. The unit has curved surfaces to avoid irritating an item being tracked, such as a pet or to conveniently attach to an item being tracked i.e. bike. A mounting structure of the internal circuitry braces the walls of the unit, to provide a robust structure and efficient use of the space. A battery is provided, which can be removed and replaced without removal of the tracking device from the item being tracked. A strapping arrangement is provided to mount the device to the item being tracked. The device interfaces with remote software in the form of an application or webpage, to enable users to establish the location of the tracking device and perform other functions such as tracking activity levels.