Thank you for your interest in the product. SONY WF-1000XM3 WF-1000XM4 New Battery LIR1254 Battery 2-piece set ★☆Beginner-Friendly Guaranteed Battery☆★ The battery surface has + - short-circuit prevention processing (red or yellow vinyl processing), so please install it as is, without peeling it off, as shown in photo 2, making sure not to mistake the + and - terminals. Because of the battery performance and the labor involved in the vinyl processing, the price is slightly higher than other companies' batteries, but even beginners can easily replace them with less risk of damaging the earphones. We perform voltage tests on each battery before shipping, so please purchase with confidence. After battery replacement, the test results with wf1000xm3 show that playback is possible for more than 5 hours. We have been sourcing high-quality products for this battery and are confident in selling it. We have received high ratings for 3 years, so we have included a warranty. We offer a 30-day peace of mind guarantee from the date of purchase, so please purchase with confidence. ※Peace of Mind Guarantee※ If there are initial defects or a sudden drop in voltage, we will exchange the product for a new one if you send it back to us, but the buyer is responsible for the shipping costs. (Caution) There are many products sold cheaply from other companies, but please be aware that many defective and faulty products are also sold at bargain prices. Compatible devices are as follows: WF-1000XM3 WF-1000XM4 WF-1000X WF-SP900 WF-SP700N WF-SP600N WF-1000X