The Z Pen Holder features the shape of a traditional 3x3, but with a cylindrical interior that is designed for holding pens and other desk accessories. It can only be rotated on 3 layers, as there is no proper 3x3 mechanism inside.The Z Pen Holder features the shape of a traditional 3x3, but with a cylindrical interior that is designed for holding pens and other desk accessories. It can only be rotated on 3 layers, as there is no proper 3x3 mechanism inside.