The "Bureau" Reference Scale 2-piece set contains an L-shaped scale which is 30 cm long on the long arm and 15 cm on the short arm, and a second straight scale which is 15 cm long.
One side of each scale is white with black print, and the other side is black with white print. These scales are made to official FBI specifications and photograph well under a variety of lighting conditions. These scales have crosshair circles which provides a means of checking and correcting perspective distortion.