Here are the photos.
First, a view of the weight plate cover showing the underside of it:
![](http://i704.photobucket.com/albums/ww48/playmofire/P1060205.jpg)
The weight is what it sounds, a metal weight which fits very tightly into the holder and which weighs 182g.
Now, a 4100 blue carriage without the weight:
![](http://i704.photobucket.com/albums/ww48/playmofire/P1060204.jpg)
and with the weight:
![](http://i704.photobucket.com/albums/ww48/playmofire/P1060202.jpg)
And, lastly, the 4111 freight wagon with the weight fitted:
![](http://i704.photobucket.com/albums/ww48/playmofire/P1060203.jpg)