Safer life starts with our products! For 820CB Replacement Garage Door Opener Safety Sensor Description: Compatible with Chamberlain garage door opener manufactured after 1997 Enhanced troubleshooting, most intuitive safety reversing sensor Low profile reduces risk of being knocked out of alignment Whenever there is an obstruction, the garage door will automatically reverse TIPS: Be sure power is NOT connected to the garage door opener BEFORE installing the safety reversing sensor. What you need to pay attention to when installing: 1. The sensor is highly aligned to prevent the receiver from being unable to receive the signal. 2. The wires are installed correctly, the white wire is connected to the white wire, and the black wire is connected to the black wire. 3. Keep the wires clean and don't get rotted, it is best to use the wiring head to install. 4. Keep the lens clean to prevent affecting signal transmission and reception. Shipping Notice: Customs Tax : Customs Tax should be paid by buyer, Seller can't support any Customs Tax. Remote Area : For Remote area, DHL/Fedex/UPS/TNT will charge extra " Remote Area Fee". P lease understanding it. Return: Returns are accepted . In case of a refund all items must be returned undamaged, in a re-sellable condition. For DOA (Defective On Arrival) items, which will be replaced or refunded, please inform us within 24 hours of arrival, please also keep all of the components and original packaging as further checking might be required. Faulty items must be returned for repair or exchange. Buyer is responsible for all shipping costs of returning an item for a refund or exchange . Contact us: 1.If you have any question, Please contact us.All message will be answered within 24 hours from Monday to Saturday. 2. Please contact us before leaving any negative or neutral feedback or opening disputes, we will work with you to solve any problems.