These scales were designed as a two-piece set, primarily for footwear and tire track impression photography.  They provides accurate reference measurements when placed evenly in the same plane in two-dimensional or three-dimensional impressions.  Excellent for verifying perspective distortion.  These rigid plastic scales have a flat, non-reflective finish to eliminate reflections during photography.  The L-shaped scale measures 30cm x 15cm and includes a separate 15cm scale.  The reversible scales are white with black printing, and the reverse side is black with white printing.  Accuracy verified with a NIST traceable standard.