Compatible with Part Number : Z52H Compatible with Laptop Models: For Sony LinkBuds S WFLS900N/B Bluetooth Earphone Battery Z52H 3.85V 55mAh Package Includes: : 2 x Battery+TOOLS Description: Replace faulty or old battery if not holding charge like it used to. Bring back new life back into your old . Have had no complaints about these great Batteries. Please ask if unsure about compatibility with your Version and Model Number.