Core i5 4200U. Batteries are not covered in any warranty. These machines are usually high specification models, and will have been regularly and professionally maintained, having many more years of hard work ahead of them.
Lenovo Thinkpad X240 - Core i5-4300U, 12.5" Screen, 8Gb Ram, 500GB HDD, WIN 11
Lenovo Thinkpad X240 - Core i5-4200U 1.6GHz - 4GB DDR3 Spares Or Repair
Lenovo ThinkPad X240 Core i5-4300U 8GB 240GB SSD Windows 10 Pro
Lenovo Thinkpad X240 Core i5 Turbo 2.9Ghz 8GB Ram 2TB SSD Windows 10 Laptops
Rome Tech CMOS Battery for Lenovo ThinkPad X240 / Lenovo ThinkPad X240I / Lenovo ThinkPad X240S / Lenovo ThinkPad X250 - Laptop Backup BIOS RTC 3V CR1632 Battery with 2 Wire Cable (1-Pack)
Lenovo ThinkPad X240 12.5" Core i5 128GB SSD (Refurbished)
