There are many different selection criteria when selecting a temperature controller product. The first question to ask is, will it be inside the control panel, or mounted outside/on the control panel? If this is going inside a panel, do multiple temperature loops need to be controlled, or just one? If controlling more than one loop, is it connecting it to a plc? If mounted on panel/on top of a control panel, does it need to be digital or analog and is the primary focus cost or features? If features are the most important thing, what panel cutout DIN size does it need to fit?