These M12x1.25mm plugs are precision machined from Stainless Steel. It features a shallow thread depth to prevent carbon build up on the lower threads. Each plug comes with M12 1mm thick copper washer. *This product is designed for monitoring purposes only whereby the user can add additional monitoring equipment and not as an OEM replacement part. Ticon Industries Inc and Stainless Bros assumes no responsibility if the product is not used for its intended purpose*