The AQ3140 COD colorimeter is CE certified, IP-67 waterproof and accepts Orion AQUAfast 16mm COD dichromate digestion tubes, available in standard 25 tube packs and new 150 bulk tube packs. The Orion AQUAfast COD165 thermoreactor is also available as a separate accessory for digestion tests. Large digital backlit display. Waterproof sample chamber.