Plastic knob retractable plungers are used in machining applications with limited space as positioners, loading pins, and indexing devices. This particular style pin comes equipped with an easy to grasp knurled knob for withdrawing and engaging the plunger. To withdraw plunger tip, pull on the knob, adjust work piece to re-align perforated holes, and release to re-engage the plunger tip. This robust, durable design is suitable for repetitive-use applications.