"Easy-to-use fixture allows full assembly and testing of any AR-15 trigger prior to installation. Aluminum angle bracket with extended length trigger pins secures trigger group to side of lower receiver. Provides a clear, unobstructed view of the sear, hammer, and disconnector engagement points while under normal spring tension. Takes the guesswork out of achieving that perfect trigger pull. Durable, Delrin dry fire block drops into magazine well for safe test firing. Great for trigger modifications, checking adjustments before installation, or for use as an armorer's training aid. A ""must-have"" for AR-15 trigger work. SPECS: Bracket - Aluminum with black, protective finish. Dry Fire Block - Delrin. Fits .154"" dia. pin holes. Includes instructions."