A notch keeps the plunger in the retracted position. 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.GN817-4-6-M8X1-B Indexing Plunger 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.