Chamber-View for AR-Type Modern Sporting Rifles is a safety block designed to fit most AR-style rifles accepting .223 caliber, 5.56mm and 6.8mm SPC ammunition.
The Chamber-View for AR-Type Modern Sporting Rifles provides instant recognition that a firearm is safe by obviously indicating a fully open action to surrounding shooters, personnel and observers. The Chamber-View also helps preserve firearm performance by preventing elements from contaminating the ejector port, magazine and barrel.
Made of 100% silicone, it is also flexible and resilient across a wide range of temperatures. Chamber-View for AR-Type Modern Sporting Rifles won’t scratch surfaces and has excellent sealing properties against environmental elements. The safety block is also water-repellant, heat-resistant and is chemically resistant to a wide range of gun cleaning solvents.
See more at http://www.chamber-view.com/.