Here's another look at the mask itself
And as for people wondering why they delayed giving Green "Arrow" a mask, well, "according to executive producer Andrew Kreisberg, the answer is multi-faceted. ”Conceptually, it was something we wanted to do because Oliver himself is evolving as the Arrow– from vigilante to hero, sort of from Arrow to Green Arrow — and we wanted to see that progression in his costume as well,” he said. “As Oliver is embracing being a hero, being a hero means stepping out of the dark and being more of a symbol, so he has to take steps to conceal his identity more.” Adding a mask also comes with logistical benefits, he said. In the second season, Oliver has found himself working much more closely with several people who don’t know his true identity — like Laurel’s father Det. Lance, for example — and it was getting harder and harder to believably hide Oliver’s face under the hood. “It’s going to allow the Arrow to interact with people who don’t know his identity in a much more organic way than having him constantly keep his head down,” says Kreisberg."
Here's the link for the whole article: http://insidetv.ew.com/2013/11/19/arrow-oliver-mask-photos/