I know what you're thinking -- it's a hand weight. Big deal. But is that really all it is? The XCO Trainer promises to "boost your cardiovascular system and increase weight loss by up to a third more" by building and toning muscles while strengthening surrounding tissue and stabilizing joints.

That sounds pretty complex to me -- let's look a little closer at what it does.

Each movement you make creates a delayed soft-impact due to the free-flowing silicone granulates within each foot-long tube. Based on the notion of "Reactive Impact," your body has to work harder to accommodate this shifting of weight, or secondary load, which generates faster results for you.Additionally, training with the XCO requires you to move in three dimensions, which is how we naturally move anyway. Not only does that make your training flexible -- you can use lots of different positions and directions -- but these natural movements maximize the benefit to even more muscles.

The XCO Trainer is available here in four sizes, ranging from the Small (1 pound) for $59.95, recommended for general fitness and rehab, to the X-Large (2.6 pounds), which sells for $79.95 and is designed for advanced and elite athletes.

Or, you can get the full XCO Walking and Running Package, which includes two tubes and a belt to hold your phone, iPod, water bottle, and XCO tubes. That package is available here for $149.95.