The Good: Despite the weighty build, Rovr's rugged, rotomolded design and heavy duty wheels offer better mobility than you'll get with any other cooler we've tested. The Bad: The Rollr 60 was several quarts less spacious than advertised, and it didn't hold the cold as well as other coolers that cost a lot less. The Bottom Line: It won't come cheap, but the Rollr 60 is a good upgrade pick for folks who lead an active outdoor lifestyle and want to bring their cooler with them wherever they go. At $400, the Rovr Rollr 60 is the most expensive cooler that I've tested, and there's a reason for that. Aside from the durable, rotomolded design, the Rollr is built around a rugged aluminum axle that supports a pair of heavy-duty, 9-inch rubber tires. That's a considerable step up from the competition, as most other rolling coolers, including the more budget-priced Igloo Latitude and Coleman Xtreme wheeled coolers, use cheap, plastic wheels and axles that might as well have been borrowed from your kid's Tonka truck.Rovr's rugged design even stands out among its most high-end competitors. Yeti has a wheeled version of its popular Tundra cooler coming later this summer that'll also cost $400, but that cooler won't offer as much capacity as the Rollr 60, and its wheels are all plastic. Orca and Bison don't offer wheeled coolers at all, though Bison does offer a $130 "hauler" cart accessory for its nonwheeled coolers. That cart brings your total cost up to $460, though -- and again, the wheels are plastic.These are the best coolers you can buy this summerBoth Yeti and Bison try to put a positive spin on their respective wheel designs by calling them "Never Flat" wheels. That's a nice try, but thick, inflatable rubber is what you want for the smoothest off-road towing.That's why the Rollr 60 is my top mobility pick among hard coolers. It didn't hold the cold quite as well as other rotomolded coolers I tested, particularly the Yeti Tundra 45 and the 58-quart Orca Classic, but it's still well worth saving up for if you need a cooler that can keep up with an active outdoor lifestyle.Rovr's wheeled cooler makes a great first impression. As I rolled it around using its aluminum handlebar, I was struck by just how sturdy and smooth the thing felt, and others in the office agreed. Our photographer and video editor Chris Monroe, who spent lots of time lugging all of the coolers I tested around, said it was his favorite design by far.At any rate, it's an obvious upgrade over flimsy wheeled coolers like the Igloo Latitude and the Coleman Xtreme that use all-plastic designs to roll around like cheap suitcases (and in general, I prefer wheeled coolers like the Rollr 60 that offer lift-and-pull, wagon-style rolling instead of the suitcase approach, which forces you to tilt the cooler at an aggressive angle). My only complaint: I wish there was a rubber grip in the center of the handlebar, since that's where you'll want to hold it when you're towing the Rollr 60 behind you with one hand.