HELP™ Differential Cover Plug (65293) by Dorman®. Material: Rubber. Dorman’s Differential Cover Plug is manufactured from high quality rubber. Durable design ensures a long service life. Safeguard your differential from potential road hazards with this top-notch differential cover. Made to exact specifications for fit, form, and function, this premium product will protect your differential against damage caused dirt, rocks, salt, or anything in between. Manufactured from the same sturdy materials as the factory cover, this reliable differential cover delivers the ultimate in quality and durability.