Increase the life of your firearm by reducing malfunctions like jamming. Cammenga's magazine dust covers block dust, dirt and other problem-causing contaminants. Magazine Well Dust Cover for M16/AR15 Style Lower Receivers. Made with a durable rubber compound impervious to ozone, water, acids, bases, grease, salts, seawater, oil, fuel and alcohol. Excellent resistance against abrasions, cuts, tears, deformation and flames. Withstands temperatures ranging from -20Adeg F to 250Adeg F. Proudly made with the highest quality in the U.S.A.