The design comprises a module of an electronic personal training device, and which comprises a display panel for providing information to a user while performing activities such as running, swimming, cycling or the like, and a 4-way button or other user input device for receiving commands from the user. The module is insertable into a strap to form a fitness watch, but can also, for example, be inserted into a suitable mount on a bicycle. The module may comprise location determining means, e.g. a global navigation satellite system (GNSS) receiver.