Thank you for viewing. *Software version is 2.3.1. If your headphones have a version of 2.0.0 or higher, you can pair them. Please be sure to check the version. The battery has been replaced with a new genuine ZeniPower Z55H battery. All functions have been confirmed to work. The results of 2 hours of continuous playback with noise canceling ON and volume at 50% are listed, so please use them as a reference when purchasing. There is some wear and tear, but there are no noticeable scratches or stains. Please check the photos. Recommended for those who have lost one side, have a malfunction, or find that the battery drains quickly. Please be sure to initialize. How to reset and initialize: https://knowledge.support.sony.jp/electronics/support/articles/00264029 Please understand that the earphones are used items before purchasing. We will clean and disinfect with alcohol before shipping. Sony Model Name...WF-1000XM4 Other features...Noise canceling