Yeah, sure. I'll start with the fourth quarter, Seth, and then work into the guidance for 2020. Fourth quarter, you saw SG&A improved 125 basis points. Three broad categories. Labor, labor related, we did leverage store labor in the fourth quarter. We saw some improvements in our marketing program as Jason McDonell comes in and looks at some of the underperforming spend. We pulled back on some of that. And then, for the fourth quarter in a row, we've seen improvements in insurance and claims, and this was really some favorability around some of our actuarial assessments. So, throughout the year, what we've seen is improvements in both the volume of claims and the severity of claims. And those are two key contributors to an actuarial valuation to estimate out into the future what you think your costs are going to be. Those are going to come down, albeit slow. So, that sort of gets into 2020. We think we're going to continue to see improvements in the areas of labor, of supply – sorry, of safety. Safety, what I just discussed. Labor, we're going to continue to leverage myday. We believe we can continue to see improvements there. We have integrations going on in the back office. We've talked about the ERP. We're going to see second half savings there. And we're also integrating AI and Worldpac. So, as we continue to get synergies around that, we'll see savings in SG&A. Stepping back to 2020, as we think about where we're going to see the expansion, we do think we're going to see savings, but we also have a significant amount of investment. Similar to what we guided last year, we're going to continue to have OpEx investment this year in marketing, in people, in supply chain and in IT. At this point, we think we're going to see more of the improvement in our margin and gross margin. And that's largely driven by two factors. First is the supply chain. And we've been working on this for a couple years now. And we said it was going to take more time. We're going to start to see those improvements in supply chain in 2020. And then, the second is category management, which is a combination of MCO, material cost optimization, private label and pricing. And the combination of those items, we really think we're going to see the benefit as we sit here today, more in gross margin and less in SG&A as we take on some of those OpEx investments within SG&A.