to get the height/angle you want while making sure it is still stable.
a bonus feature of this lap stand is that the upright curved piece that holds the frame clamp can also used as an extension piece on the floor stand (best used on the regular stand, not the travel mate). if you have both a lap stand and a floor stand, when you are not using the lap stand you can remove this piece from it and attach it to the floor stand to get an additional 9" of reach (of course you can also buy this extension piece separately).
the lap stand base measures 16" wide by 10" and 