It's the first truyly portable Black & White transmission Densitometer with 0 to 4 D measuring range and +0.02 D accuracy. Its rugged construction makes it ideal for use in the field as well as laboratories. The self contained light source make it independent and reliable. Push button zero and read contraols make the operation very simple. Advanced low power circuitry allows a long battery life for the dry cells or optional rechargeable cells. Applications - a) Industrial and medical radiography b) Opacity of foil stock like paper, films, cloth, plastic sheets, etc. c) Metallizing of films, glass and foils