This easy to use apparatus allows full assembly and testing of any AR-15 trigger set up prior to installation on your rifle. The AR15 Trigger Jig allows you to clearly see the sear, hammer, and disconnector engagement points while under normal spring tension. The Trigger Jig enables you to dry fire the trigger without damaging the jig or other internal parts and make necessary adjustments while checking functionality. Allows you to mount the jig in a vise and adjust for trigger pull without having the rifle present. Consider it the Armorer&';s and best friend. It&';s also a great training aid for trigger assembly installation and minimizes the chance scratching your rifle.