Before you order a sleeve for your keyboard, please take some time to see which one it should be. The older Wireless Keyboard, which is still sold, is slightly larger than the new one. You can easily recognize it from the side. If it looks "rolled up" (picture on the left), you have the Wireless Keyboard. If it has a filled in wedge shape like the picture on the right, you have the Magic Keyboard.
The same is true for the Trackpad. On the left (rolled up side) the Magic Trackpad, on the right (wedged side) the Magic Trackpad 2.
You can order a sleeve here for both Apple keyboards and Trackpads.