Product review (5 stars): Measure what you need first, order this second, and cut a little bit off third. No problems! Works great!
I'm thankful for the few reviewers that suggested slicing a very thin piece along the opening "lines". I did this prior to installing using a straight edge razor on the cutting board. It works beautifully, drains without issue and most importantly it fits the opening! My previous one looked identical yet was just old, and had shrunk up and had always drained too slow which caused a disgusting buildup to acquire....I'm so glad I found this to be exactly what I needed.