It uses green ALPS which are basically white alps with a softer spring. They are similar to MX blues but have a higher actuation point and have a slighty higher actuation force. The build quality is not quite on par with the rest of the Ducky lineup, but it's not bad. My biggest complaint with mine is that it does not sit flat on my desk. Its not too noticable when typing but I still like to slide a credit card under one of the feet to keep it stable.
That being said, I still use it over my Rosewill which is of a much higher quality but uses MX reds. I don't think ALPS get enough recognition in the mechanical keyboard world.