Each Tree Classics pre-lit Christmas tree is strung with high quality Worry-Free ™ lights where if a bulb burns out, the rest of the bulbs stay lit! In the rare case that some of your bulbs burn out, you may order our Bulb Replacement Kit. Each Kit comes equipped with 50 bulbs and 4 fuses. Please, look at the bulbs of your pre-lit Christmas tree , to ensure that you purchase the correct replacement bulb for your product. If you see a T-shaped tab attached to the bulb (as in the photo), then order the Worry-Free ™ Bulb Replacement Kit.