The shutter is equipped with a battery (CR2025) that is included.
With a button on the timer, the camera can be triggered remotely. The D40 supported the following functions:
- Remote release / remote triggering with 2 sec delay:
The lens is thrown into focus (if it is set to auto-focus) and the camera
- Long-term exposure:
The exposure is started with the first time you press the trigger and ended with the 2nd keystroke.
The range of the trigger is relatively large, 10m work with visual contact, indirectly, that is behind the camera, but within a closed space, I can cause no problems to 5m. Longer distances I have not tested.
Conclusion: Useful accessories for little money!