Ada Png Size Reducer at Mac App Store analyse

What does Ada Png Size Reducer can do? Are be troubled with the large size of the App? 1)Reduce the file size of png by 40%-70% 2)Still keep the image quality after compressing the png file largely. 3)There is no obvious different between the original file and the compressed one 4)Help to reduce the size of your App, because a lot of png files are used in app. 5)Still keep the alpha channel of the PNG Files