Lenovo ThinkPad Battery 61 (Standard) Capacity: 24Wh. Design: Slim, flush-mount design that does not protrude from the bottom of the laptop. Lenovo ThinkPad Battery 61 (Extended) Capacity: 48Wh. Design: A mid-range option providing a balance of weight and runtime. Lenovo ThinkPad Battery 61 (High Capacity) Capacity: 72Wh / 6.4~6.6 Ah. Voltage: 10.8V to 11.4V depending on specific cell configuration. Key Feature: According to Lenovo Support, it includes a Safeguard chip that authenticates with the system to ensure it is a genuine part. Note: This battery is physically larger and will tilt the back of the laptop up
