What the future of treadmills looks like. The ingenious ACS? electronically adjustable cushion system on the TR33 allows the user to adjust the softness or firmness of their treadmill deck to meet their specific needs, reducing heel strike force by up to 50%! Breakthrough programming such as Glute Trainer, Personal Trainer, Heart Rate Zone Trainer and Personal CardioAdvisor? allow the user to workout and monitor their progress like never before. Overall this high performance treadmill is the pinnacle of technology, style and durability.