Abstract: A self contained light source consisting of a metal cylinder, preferably aluminum, encasing a battery threaded into one end of the aluminum cylinder there being a non conducting insulator which is manufactured to fit into bore of a commercial transparent archers nock. Located in hollow bore of said commercial nock there being a L.E.D. which is energized by screwing nock assembly into aluminum cylinder there by completing electrical circuit. The L.E.D. is selected to impose the proper current demand on the battery, which by its size becomes self limiting and is unable to burn out the L.E.D., there by eliminating all other electrical voltage controlling devices. The above described components form a unit assembly which may be glued into any commercial tubular arrow with minor modifications to the arrow.