True Z5 treadmills have TRUE's patented Soft System deck. The front third of the deck is softer, so that when your foot strikes the tread belt, it reduces the impact. As your foot moves back along the belt, the surface stabilizes to give you a firm push-off. This means significantly less stress on your ankles, knees, hips, and back. It also reduces that annoying bouncy feeling that you can get with other treadmills. In addition, the Z5 offers an orthopedic belt that reduces foot and leg stress even further. Rather than using lightweight aluminum, all TRUE treadmills feature heavy-gauge, robotically welded steel throughout for superior stability, durability and performance. This helps ensure that you and your TRUE will be together for years to come. The TRUE Z5 treadmill features a state-of-the-art motor that, when coupled with its proprietary belt and deck system, gives you the quietest, smoothest workout possible without disturbing other members of your household or your neighbors. You can also easily enjoy your favorite TV show or music while you use your TRUE treadmill.