As well as being balanced by weight, this twenty sided die is numbered to be numerically balanced, so that it gives as fair a roll as possible. The layout used for the numbering was developed by Robert Bosch, Robert Fathauer, and Henry Segerman from The Dice Lab, and injection molded dice of their design are available at the MathArtFun webshop
The shape of all dice in this set was designed by indenting the center of each face along sharp geometric edges, which gives the dice a faceted appearance as if they were grown as crystals or made from folded paper. The numbers are designed as cut-outs in the sides, and the dark interior makes them stand out well against the metal of the sides. (For the best readability choose a light finish.) Because this die is made from steel it has a nice heft to it, but because it is hollow it is not too heavy and it will roll well.
You can find a full polyhedral set, and individual dice with different numbers of faces in this same design in the Faceted Dice category
in my shop. I also sell a d20 with spindown numbering for use as a life counter.