The Hellige pocket model is an extremely convenient comparator for use in the plant, laboratory, or field. Whole apparatus only measures 3.75"" x 3.75"" x 1.5"". Housing is made of molded phenolic. Supplied with two graduated square test tubes. Bottle with Bakelite screw cap for indicator solution and dropping pipet for measuring indicator are included. One colour disc is needed with the appropriate indicator. Colour discs are not included.