A COD Digestion Apparatus typically features an aluminum heating block with cavities for multiple reaction vessels (e.g., 15 samples), a digital temperature controller, and a timer for a programmed digestion period (often 2 hours) at a controlled temperature, such as 150°C. Key specifications include the temperature range (up to 180°C or higher), the number and size of reaction vessels (e.g., 38mm dia., 20ml sample), the type of heating system (solid block with air condensers), and construction (mild steel cabinet with insulation).