Lenovo U31-70 Hard drive/SSD Replacement - iFixit Repair Guide
Lenovo U31-70 Laptop Repair - iFixit
Lenovo U31-70 13.3" Intel Core i5-5200U 2.2GHz / 8GB / 500GB vs Samsung ATIV Book 9 Plus 13.3" Intel Core i5-5200U 2.2GHz / 4GB / 128GB: What is the difference?
Lenovo U31-70 Hard drive/SSD Replacement - iFixit Repair Guide