The signal head will accommodate our 606 size Tri-color LED. VERY Detailed instructions are included along with painting and finishing tips and a history of searchlight signals. These signals are based on Southern Pacific prototypes but can be found on other rail lines. The kits contain a brass target that has been stamp formed just like the prototype. The kits contain parts to make single, double or dwarf versions. LEDs, if desired, must be ordered separately. UPDATE: We have updated this signal head by including a small screw (Button head TorX Screw - 000-120 Thread 3/32" Long) that will secure the head to the bracket. This will make this connection more secure. You will need a IP1 Torx Plus Driver. We sell these drivers on our website under the Paint/Tools drop down menu.