Number Sony Xm4 Best — Serial

The Sony WH-1000XM4 headphones are widely regarded as some of the best noise-canceling headphones on the market. Their popularity, however, has a downside: a flooded market of counterfeits, refurbished units sold as new, and stolen goods. Whether you are buying a used pair, selling your old ones, or trying to register your device for warranty support, the serial number is the single most important identifier you need.