For 3.75" figures, to display the block upright.
For the version that came with the TVC Jabba's Palace playset, add a small screw or piece of metal in the provided space for the magnet to attach. For all others, a bit of Blu-Tack or something similar should hold it in place pretty well; it's not exactly necessary, but recommended.
In the picture, the stand is glued to a regular 2" round figure stand to fit in with the rest of the figures I have on display; that is also not necessary.