Bought this cooktop to replace an existing GE cooktop installed 20 years ago. We prefer the knobs as the smoothtop models seemed more difficult to see and manipulate the controls with our old eyes. The cooktop fit perfectly into the existing cutout. It was relatively simple to remove the old cooktop and install the new one myself. We love the new lock function as we have small grandchildren. Would rate the cooktop five stars if the control numbering was a bit larger with more contrast for visual clarity.