Need this for my new D4 extra battery.
Will this work on a d4s?
Yes. I have it on the same batteries that I use with the D4. The chamber cover is used on both cameras.
Does this fit new Df camera?
No Way! The Df uses a smaller battery that fits into a compartment in the bottom of the camera. The compartment has its own door as a part of the camera. The battery is an EN-EL14a. The battery is common to the Coolpix.