A system including a portable object and a portable object holder is disclosed. Preferably, the portable object is an electronic device such as a flash memory drive such as a USB flash drive. According to some embodiments, when the portable object and the portable object holder are attached to each other, the combination is convenient for a user to carry in her pocket. While detached from each other, the portable object holder is retained in a state where the portable object holder is inconvenient for a user to carry in her pocket. Thus, the user may be less likely to forget the electronic device after use, and may be more likely to remember to replace the electronic device in or on the device holder. According to some embodiments, the portable object holder has a first state and a second state. Detachment of the portable object from the portable object holder is operative to cause the device holder to adopt the second state, where at least one dimension of the device holder is increased. Formulae relating lengths of dimensions of rectangular prisms which minimally circumscribe the object holder and/or the portable object in the first and second states are provided In some embodiments, the "inconvenient" nature of the second state may be provided by increased maximum localized contact pressure, for example, due to a localized projection or spike which provides this increased contact pressure only in the second state.