Like NEW, Used few time, fully tested with New NiCad battery Pack The 331C instrument is a battery operated hand-held B/W Transmission Densitometer that has achieved the accuracy and stability of our A.C. powered versions. The unique size and shape makes it an ideal totable 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 331C measures Density and Density Difference.