Abstract: A device for application of even pressure on a plunger head includes: a center rod with a pressure plate affixed at a first end and a back plate positioned adjacent to a second end; a positioning spring adjacent to the pressure plate at a surface distal to the center rod; a positioning plate adjacent to an end of the positioning spring distal to the pressure plate; a housing including an aperture at a position adjacent to a distal surface of the positioning plate; a main spring surrounding the center rod between the back plate and the pressure plate; and a mechanism positioned to move the center rod between the pressure plate and the back plate, the mechanism positioned to compress the main spring between the pressure plate and the back plate in response to force applied by a user.