Unique head design allows the user to apply or remove this plug by hand or with a 12 point socket head, screwdriver or wrench. Used to protect NPT threaded ports. Optional O-ring gives this part a watertight seal for superior leakage protection. Recommended when strength and abrasion resistance are desired. The nylon material absorbs paint, keeping paint flakes to a minimum. Nylon is able to withstand higher temperatures than HDPE. Nylon is recommended for intermittent temperatures of 230F (110C) to -40F (-40C).