STRUCTURE: The internal casing is in AISI 304 stainless steel (or AISI 316 upon request) with rounded angles for easy cleaning; the external cabinet is a plasticised, zinc-plated steel sheet; the insulation is in polyurethane resin, foamed on site, with a density of about 40 Kg/m2 and a noticeable average thickness: 190 mm. CFC-, HCFC-free; the door is placed on the upper part, mounted on self-balancing hinges; internal counter doors (in plastic-coated foamed polyurethane resin) sliding on a special track; it has a triple silicone rubber seal, welded joints, heated by the refrigerant itself and with virtually unlimited duration. It has lock and key to close it. Standard equipment includes a pressure-compensation valve to facilitate the operation of opening the door. The freezer comes complete with pivoting wheels to facilitate transportation and placement inside the laboratory. REFRIGERATION: The refrigeration system consists of three stages and is fully sealed; it uses three cascading circuits, three silent, airtight compressors and a high refrigerating capacity from 1.2 HP and 1.7 HP. Pressure gauges for max. and min. pressure for maximum compressor safety. Extensive air condensation surfaces to compensate even the harshest environmental and work conditions. The expansion of the refrigerating fluids is obtained through capillary tubes. Absolutely non-CFC and non-HCFC refrigerants to provide maximum environmental protection, which are also non-flammable, non-explosive and non-toxic.