Scilogex MS7-H550-Pro Ceramic-Glass Digital LCD Magnetic Hotplate Stirrer, 7" x 7" Plate Size, 110V

Final review after a month trying to work through the external sensor problem with the manufacturer:Summary: If you don't care about using the optional external sensor, this unit is excellent. With the sensor it is slow, erratic, and unpredictable.Pros: Build quality, fit and finish of the unit are excellent. It has a heavy cast base as expected, sits dead level, and operates with no noise or vibration. It is impressively silent; there is no buzzing, and no 'plinking' during heating or cooling, the motor noise is faint. The interface is intuitive. It measures to have a true 1000W of heating, and makes 550C at the plate and 1500RPM with a 2" stirbar easily. When used without an external temperature sensor, the unit appears to be reliable and well behaved. It can bring 1L of water in a glass flask to a hard boil in 19 minutes.Cons: Erratic, slow, unpredictable behavior with the external sensor. Multiple tests run with the external sensor and water between 80 and 100C showed the unit required hours to slowly approach setpoints in a meandering pattern, unexpectedly backed off setpoints by 10-15C without warning, and occasionally stopped paying any attention to sensor readings at all. Throughout the weird behavior, the sensor temperature displayed accurately. My two units, with two different sensors, showed identical behavior problems. The manufacturer eventually stated this was probably the way the units were supposed to work (but wanted me to send them in for testing). My Barnstead/Thermolyne units are capable of hitting a setpoint quickly and without fuss when using an external sensor, so I'm not inclined to believe this behavior is intentional.Niggles: The rotary knobs on the front don't register or move settings backwards when turned too fast (which is to say turned very fast at all). The manual appears to be a cut-and-paste from an earlier unit and describes settings/behaviors that don't exist. The external probe can't be used only for temperature readout. If it's plugged in, setpoints can only be relative to the sensor. The external probe for this unit is not a standard type; 99.99% of hotplates use a 100 ohm sensor. This unit uses a 1k-ohm sensor. Amazon doesn't allow sensor returns, so if you buy it, you're stuck with it and can't use it on some other better-behaved model.