There are dozens of treadmills on the market, but nearly all of them are built with a thick base and a bulky, command-center style handrail. The Treadly Ultra-Thin Treadmill is different. It weighs just 55 lbs, is just 3.5 inches thick, and uses infrared sensors to track your foot position and adjust the speed accordingly. For walks up to 3.7 mph, you don't even need to put up the handrail, but raise it, and the maximum speed will increase to a steady 5 mph job. An LCD screen on the front displays key workout metrics, and thanks to its svelte design, it's easy to store, and also works great as a companion for a standing desk.