several years ago. In the original blog entry you'll find a more thorough description of the product itself. Basically, it's a set of geometric blocks that are used to build structures that require balance or an eye for 3-D (depending on which book you're using.) My kids began using the series at ages 4 and 7. Now ages 6 and 10, I'm amazed at how the activities continue to challenge them.
Having recently purchased another set of blocks, a friend's visit inspired an "Equilibrio Competition." They opened the book so both could see the structure and then raced to see who could successfully build it first. When one finished, he helped the other to figure it out.
This would make such a good addition to geometry, whether at home or school, providing immense opportunity for differentiation. It screams "Math Station!"
Disclaimer: I bought my own set--two sets of blocks and all 3 books--and have no contact with the company that produces it. If you use the Amazon link to buy your own, Grace and Hope (foster care for kids in China) will make a few cents (at no cost to you.)