Abstract: A user replaceable case for a touch operated handheld device, the case being arranged for at least partially enveloping the device when the case is applied to the device, the case comprising a device interface for digitally interfacing with the device when the case is applied to the device; a physical control means arranged on an outer surface of the case for providing tactile feedback to a user when operating the physical control means; and a controller for i) sensing an operation of the physical control means by the user, and ii) based on the operation, sending an instruction to the device via the device interface for controlling the device.