A rare item that can be found in the barracks, rangefinders allow you to accurately find the range of a target quickly, making it extremely valuable for snipers. Taking up the Binoculars slot, rangefinders can be brought up by pressing 'B'.
Another useful aspect of the rangefinder is its built-in night vision. This is turned on by pressing "N" while you are looking through the rangefinder.
To a degree, it is possible to find a range without the range finder. When scrolling to bring up the list of available actions, a distance will be shown with the text in the centre of the screen. However, this only works on some certain servers.