The Modern Keyboard is designed for Windows Hello — the biometic login feature found in Windows 10. It features Bluetooth 4.0/4.1 and a wireless range of up to 50 feet. Coming in at $129.99, the big feature is the fingerprint sensor.
The Keyboard is the successor to the Surface Keyboard, and looks identical. The only changes are a new fingerprint reader and the ability to use a cable for a wired connection instead of wireless.