This update to our US&S H2 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-red, green, yellow (not included but sold separately) will fit directly into the signal head -one for each head. 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 smaller 402 size LEDs. The 402's are individual colors as well and you will need to put two in the same head if you want the option of two different colors in the same head or there again, you can purchase the Tri-Color LED0001 with the option of red, yellow or green from the same LED.