A manually-operated device typically used in the laboratory to withdraw, transfer, and inject minute volumes of fluid materials (e.g., microlitres or smaller). The device is typically hand-held and operates through an internal mechanism powered by finger depressions of the user; it can have a single channel or a multichannel piston/cylinder assembly. The device transfers consistent volumes of substance into one or several receptacles simultaneously. The device may be factory pre-set to deliver a given volume, or may have user-selectable volumes within a useful volume range.