Here is the information on the mini erasers! If your kids have not heard about them and you can surprise them for Christmas I can't think of a better stocking stuffer. They have been all the rage around here for about a year.
Our Michael's craft store just got some knock offs for 4 for a $1.00 hanging on an end cap. If you have a "Five Below" store they sell them too. No one uses them for erasers but they come apart in different parts and are really fun.