This easy to use apparatus allows full assembly and testing of any AR15 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 Armorers and best friend. Its also a great training aid for trigger assembly installation and minimizes the chance scratching your rifle.