The iO Dock is fully certified by Apple to work with iPad, iPad 2 and iPad (3rd gen). If you’re using the iO Dock with the original iPad, you don’t need an adapter.
Currently, the iO Dock comes with a black iPad 2 adapter in the box. This new adapter, pictured above, is gray and fits both iPad 2 and iPad (3rd gen). With this adapter, your iPad 2 or iPad (3rd gen) will fit seamlessly into your iO Dock.