Black molded plastic with VOX logo. As used on various '70s-'80s amps. Fits to an opening slightly larger than 5.486" X 1.370". I measured 5.615" X 1.601" at the upper lip. Vent is held in place by two small nails (not included...) on the inside of the long ends. I purchased these in England along with many other used parts over twenty five years ago. Good Used Working Condition.