Important Characteristics Temperature range (model 23): 00C to 1000C Temperature range (models 53, 115, 240, 400, 720): -50C to 1000C APT.lineTM preheating chamber technology Cooling with compressor cooling unit Door heating system from 240liters Adjustable fan speed Controller with time-segment and real-time proggamming Elapsed time indicator Inner door made of tempered safety glass 2 stainless steel racks Units up to 115liters are stackable Access port with silicone plug from 240 liters Class 3.1 independent temperature safety device (DIN 12880) with visual and audible temperature alarm Computer interface:RS 422