Super Bright Bulbs. Steady burning or two way flashing, If one bulb burns out the rest stay lit. Connect up to 3 sets end to end. For Indoor / Outdoor Use 120 V 60Hz. Blinking Feature: This 100 light set consists of 2 independent 50 light circuits. Each circuit can be made to blink by replacing ANY 1 of the bulbs in that circuit with a red-tipped blinking bulb, There are 4 spare bulbs included – 2 red-tipped blinking bulbs and 2 steady burning bulbs. Use 2.5 volt replacement bulbs only.