It measures in pixels. It can be an ideal complement to know the size and position of some objects.
Drag&Drop it in any place in the screen. It offers three different and attractive skins, so you can have it in orange, blue or green.
Clic it and change the position of the ruler, so youll know how long is anything you want. It measures up to 1300 pixels.
Pixel Ruler shows the value of the position where the mouse is and youll have to calculate it.