American 45 Degree Offset Rapid Transition BUIS Backup Iron Sights For Rifles Comes With Manual Designed for the AR-15/M4/M16/AR10 platform. Torture Tested & Proven By Military, Law Enforcement & Competition Shooters. Precision Machined From Aircraft Grade 7075 Aluminum & QC'd In The USA. (extremely durable & will hold up to anything you can throw at it) Ambidextrous sights easily and securely mount to Picatinny rails using a flathead screwdriver. BUIS lets you quickly transition from a magnified optic to iron sights