A notch keeps the plunger in the retracted position.
To achieve this, the knob is rotated by 90 degrees after being retracted. This indexing plunger has the unique feature of the pull knob partially enclosing the top of the plunger body, allowing less debris to enter into the mechanism..Type G and GK with threaded stem are for applications where a special knob or attachment is required, or for such cases where the spindle is linked directly to an operating mechanism.