A peripheral unit comprises a housing having a portion configured to engage with a handheld host device of various sizes and electrical configurations. An attachment mechanism is associated with the housing, being used to selectively secure the housing to the handheld host device to form a one-piece apparatus suitable for handheld use. The attachment mechanism is secured to the host device by selective adjustment of the size to adapt to a host device. In addition, the peripheral unit may provide a universal connection to at least one electrical connector of the host device, to provide added input-output functions to the operation of the combined system.