CHEMetrics COD Vials Kit (K-7355) comes in a cardboard box and contains everything needed to perform up to 149 tests (except distilled water): 150 vials and instruction book. All COD Kits require the use of a Digestor Block and the V-2000 Photometer, a COD Photometer, or a spectrophotometer capable of accepting a 16 mm round cell. Instruments sold separately. A fresh reagent ampoule blank must be prepared for each series of tests; therefore the number of samples that can be tested with each kit will vary.