Sturdy metal chassis. Keys are compact but not "mini" considering how akai or m-audio use the term. They are more like playing regular sized keys than say a keystation mini32. Key resistance is also fine. I have seen review complaining about the black keys being to heavy, but I did not find it to be so. Perhaps they adjusted it along the way. The knobs and buttons are programable and sufficient for my purposes. The only thing I don't like is the touch strips for modulation and pitchbend. They work fine I suppose, but they are kind of a different thing than what I am used to.