Thermoblock dry heaters with interchangeable test tube blocks. Steel housing oven coated with acidproof epoxy paint ; block tanks in aluminium for uniform heating. Value adjustment and control in analog versions obtained through a PB electronic thermoregulator with a graduated (°C) thermocouple probe ; digital models are fitted with digital thermoregulator with PID microprocessor and PT 100 probe , which ensure temperature accuracy. Thermoblock is heated by resistances placed beneath the tanks and all models are fitted with an ON / OFF switch with green light.