A press-fit ball plunger, also known as a spring loaded plunger, is a type of plunger that uses a spring to provide tension. The ball is placed in a socket, and the spring is compressed between the ball and the socket. This tension creates a press-fit, which allows the plunger to grip the surface surrounding the socket. When the plunger is pushed down, the press-fit is released and the ball pops up, creating suction. The press-fit ball plunger is commonly used in applications where a strong seal is needed, such as in plumbing and automotive applications.