Why do I need ...

I need it because I do not ever want to switch between different paper sizes or when I print a lot, do not constantly have the paper setting.

For the paper tray no driver is necessary, it is quickly and easily unpacked and easily installed.
Well, during the installation, keep in mind beforehand that
- The printer by the paper tray is higher
- You have to lift the printer and then place it on the tray -> Observe weight of the printer and make it possibly for two, possibly pull cable first, in any case: the printer before installing the times off!

What is not mentioned, and I had known like before buying: in this Erweterungspapierfach only A4 size paper can be inserted.
In my view, not so bad, because you can configure the tray 1 in accordance with their own ideas for different paper sizes.

So I have, for example, in the paper tray 1 small photo paper in the tray and the 2 A4 paper.

Alternatively, you can insert plain paper in a paper tray if necessary and stronger in the second paper tray / carton paper. Very handy when printing expose or handouts.

Thus, you save the paper tray you time and hassle.