The product model/number can be found on the underside of the headband, right above the left ear cup.
4PXXXXX is the most common structure but it may start with something else. If you are unsure, please send a screenshot or picture to our tech support team to help ID the product for you. The name of the product is also included and be searched under the Headsets list on the left-hand side column to access support articles.

Kingston models will start with KHX- or HX-. and underneath that, you should also have a number starting with 3500.
Make sure to include both when talking to our tech support team.