You know the socket wrench, it's the one who is red.
If you're like me, you read the first sentence and didn't think anything was wrong with it. Hopefully the second sentence drew some red flags. Even my "polished" MS was peppered with thats, that should have been whos, two months ago, but not anymore.
Use who when talking about a person and that when you're talking about an object.
You know the socket wrench, it's the one that is red.
Does who vs. that ever confuse you?