National Tree 70 Bulb Dual Color Low Voltage LED Lights, Add On Set (LS21-802-70) ADD-ON light string set includes 70-bulb low voltage LED Dual Color lights Requires one STARTER SET for operation, model # LS21-801-70 (sold separately) Up to seven ADD-ON strings can be connected to one STARTER SET Lights change from warm white to multicolor with the press of a button Indoor use only