The invention relates to a process for measuring particle size by measuring the attenuation of radiation after its passage through a defined measuring section containing a disperse system. An improved roll-able dumbbell utilizing gravitation and roll-resistance is presented having a handle and a plurality of circular weights attached to its ends. This IC card compares the intermediate information with the fingerprint information, and makes authentication information usable for an electronic authentication upon matching. Embodiments implement a target imaging mode to provide a volume image of a relatively small target area corresponding to the identified target of interest.