To go with the new Surface Pro 4, Microsoft introduced a new Type Cover. This is the thinnest Type Cover that Microsoft has made, and features new keys, a bigger trackpad, and of course, multiple colors.
The trackpad on the Surface Pro 4 Type Cover is 40% larger than that on the previous cover. It's a 5-point multitouch glass trackpad as well. It also features new keys, with 1.3mm key travel, and 19mm space from key to key. The new Type Cover also features a fingerprint sensor, allowing it to work with the Window Hello biometric login feature on Windows 10. The cover will work with the Surface Pro 4, as well as the Surface Pro 3.