* drawable-ldpi (120 dpi, Low density screen) - 36px x 36px
* drawable-mdpi (160 dpi, Medium density screen) - 48px x 48px
* drawable-hdpi (240 dpi, High density screen) - 72px x 72px
* drawable-xhdpi (320 dpi, Extra-high density screen) - 96px x 96px
* drawable-xxhdpi (480 dpi, Extra-high density screen) - 144px x 144px
