An electrical device such as a portable communications device, domestic or personal care appliance has a main body adapted to couple to an accessory which may be in the form of a tool attachable to the main body or a housing portion. The accessory carries a passive data storage device having a memory (59) storing control data for controlling an operation or affecting a function of the device. The passive data storage device is arranged to derive a power supply from the main body when a first coupler carried by the main body is placed in proximity to a second coupler carried by the accessory (3). Where the electrical device is a portable communications device, then the accessory may be, for example, a fascia. The coupling between the first and second couplers may be inductive or capacitive.