Most impactful tool for your industry?

I'm a handyman and remodeler, and nothing was as big of an upgrade for me as moving from a pickup truck to a full size van (Ford Transit). The ability to organize all my tools along the sides and still have room for materials down the center was a game changer. It's also tall enough for me to walk through without stooping! When I made the upgrade, I felt like I was getting jobs done almost twice as fast.