This Dwarf signal is designed to allow you to build a more prototypical single or double assembly using the included parts. Our Tri-Color LED # LED0001 (not included but sold separately) will fit directly into the signal head -two LEDs required. If you want an individual color LED in the head then our 603 size LEDs sold in a variety of colors will work. If you want two colors only in the head then we suggest our 402 size LEDs.