0.126 - 0.250 Inch Grip 3/16 Inch Dia x 0.531 Inch Polished 5056 Aluminum Dome Head Blind RivetClosed End Rivets are used when a weather proof leak proof seal is needed. Its completely closed end design prevents liquids moisture air and other contaminants from entering the riveted hole and or the rivet itself. the Closed End rivet design guarantees the mandrel head is fully retained within the rivet. Aluminum Steel Closed End rivets have an aluminum bright polished rivet to resist oxidation and a steel phosphate coated mandrel for improved