Dear customers who are planning to purchase in bulk, please note that due to the factory price sales, returns and exchanges are not supported for non-quality issues. Due to the uniqueness of the LED lights, many problems are often caused by improper operations by the contractors. Please do not untie the lights upon receipt, but first plug them in and test them before setting them up. Once the lights are untied, we only provide warranty services. If you are purchasing this type of LED lights for the first time, please consult us more. We welcome your call for cooperation.