Each Bose product has a unique serial number or a 4-digit code located on the product or original packaging. Most serial numbers can be found on the back or bottom of the product, and they’re typically near a barcode. Most serial numbers are 17-digits long (or 4-digits long for some headphones) and can include letters and numbers.
In addition, products compatible with the Bose® Connect app, the Bose Music app, the Bose Sleep app or the Bose Hear app will display the serial number in the app under Settings > Product Info.
Here’s an example of what a serial number on a product can look like: