X-rite 331 & 334 Operation manual On CD. The 331 instrument is a battery operated hand-held B/W Transmission Densitometer that has achieved the accuracy and stability of our A. The unique size and shape makes it an ideal to table instrument for use in the plant, the lab, or on the road. The instrument has its own light source and illumination area. Push-button control of display power, lamp, and zero make the instrument easy to use.The 331 measures Density and Density Difference. Designated trademarks, brand names and brands appearing in our ads, are the property of their respective owners. This item is in the category "Business & Industrial\Printing & Graphic Arts\Printing & Graphic Essentials\Densitometers". The seller is "smartbuysonly-com" and is located in this country: US. This item can be shipped worldwide.