A fluid pressurizing and displacement device which is configured for both macro movement and micro movement of a plunger. In order to execute micro movement of the plunger, a user need only rotate the plunger； to execute macro movement of the plunger, a user need only push or pull the plunger. This simplicity in use is possible because a half-nut (or other suitable structure within the device) remains engaged with the plunger, except when the plunger is being pushed or pulled by its operator. All user motions are simple and intuitive.
