SONY WF-1000XM4 Silver (White) Right (R) earbud only. For those whose earbud battery has deteriorated or who have lost their earbud. Since Sony's paid repair service seems expensive. The firmware version is the latest version v2.1.0, and it cannot be re-paired and used with the older v1.X.X. Please check the explanation below and confirm the version you have before applying. I will also confirm before shipping, so please be sure to reply. The battery has been replaced with a new genuine Z55H, and I will show the battery level displayed in the app. It shows 77% after 3 hours, and although it depends on the conditions, it should work sufficiently as it is a new battery. The silicone rubber has been glued after the battery replacement. Playback, microphone, wearing sensor, and touch sensor have been confirmed, and the sound quality was confirmed only with my own ears, and I found no abnormalities. The exterior is a good used item with few scratches. Please check the photos. It is small, so it will be shipped by post. This is a used item that has been maintained by an individual. It is not new and there is no warranty, so please only those who understand. Series...WF series Model...WF-1000XM4 Other features...Noise canceling Please note: About the firmware version Connect the XM4 to your smartphone and check with the SONY Sound connect app (formerly Headphones Connect) to confirm that it is v2.1.0. Within the tested range, it can be paired with v2.0.0 or v2.0.1. There is a possibility that the version update may not go smoothly, but after trying 4-5 times, it can be updated if you try a few times with two v2 devices. # If both left and right earbuds are present and automatic updates are enabled, it should be v2.1.0. If it is v2.0.1, etc., please update if possible. # If you have lost one earbud and can connect to your smartphone, check the version in the Sound connect app and consult with me. If you cannot connect or do not know the version, it may be safer to purchase a pair. Please consult with me before purchasing. Please check the firmware and Sound connect app on the SONY website. 5A5Ri