a smartcard unit includes at least a smartcard and an attachment enabling the smartcard unit to be worn by a user . the smartcard is accessible to an external reader . a reader unit interfaces with the smartcard to enable an external computer to communicate with the smartcard . the smartcard unit or the reader unit has structure to align the reader unit relative to the smartcard unit in an alignment for communicative interfacing while the smartcard unit is being worn . the smartcard unit or the reader unit has a retainer to secure the reader unit in alignment relative to the smartcard so that the smartcard unit is reversibly separable from the reader unit without damage , in response to a force less than is necessary to detach or damage another part of said system , other than along a longitudinal axis of the smartcard or of a pair of components being separated .