If you have been watching arrow (you really should be) then you know that Ray Palmer has been working on his suit Atom suit for quite some time. We have seen little bits and pieces here and there, but now we finally get the chance to see the whole thing put together.
What we know is that this is, at present, only a suit of armor. There is no word on whether it currently has the ability to make him change size, (something that could prove troublesome on a TV show budget) but as Arrow likes the slow burn that is still a possibility down the line.
We know that Ray Palmer is heading to central city to get some help with his new suit, so we can expect to see him crossover and team-up with Flash for a good time.