The 54139 is a Color-Keyed copper one-hole lug designed for terminating #4 AWG wire. It features a standard barrel with a peep hole, which allows for visual verification of proper wire insertion before crimping. This lug accommodates a 5/16 inch stud and is rated for applications up to 35 kV. Constructed from copper with a tin-plated surface for corrosion resistance, it is color-coded gray and corresponds to die code 29 for correct tool selection. Its straight design makes it suitable for a wide range of standard electrical termination applications.