Hotplates are made of smoothly finished cast-iron with central expansion recesses. Overflow edge and cover hood are made of rust-proof stainless steel. Each unit has a screw-in fitting for a supporting retort rod. Designed for a maximum temperature of 400°C, infinitely variable from 10 to 100%. 2 pilot lamps, 230 V AC, 100% duty cycle. Models SGR... can be controlled in addition by a contact thermometer. The customary electronic K thermometers can be attached also directly.