These high precision glass scales offer you the following benefits: They are ideal for checking the magnification accuracy of profile projectors and microscopes, as well as the table feed accuracy of measuring equipment. This unit has two scales 10 X 0.005 and 20 X 0.001. The Scale dimensions are 24 inches but the over all length is 25.5 inches. Included is a nice felt and leatherette storage box. This item is new from a former dealer. Thanks for looking!