I have the Kohler Executive Chef sink.  This fits perfectly. I had the rubber sink mats before, but they became slimy and nasty looking within 5 days.  I had to disinfect them and use a brush to clean the slime. Now I do not have that problem.  Thanks Kohler.  My only compliant is that no one, not even Kohler, makes this rack to fit the right had sink. I would buy it in a minute if I could find one.
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