The Body Power StepTrac BST800 is exclusively designed better and safer – the Curve-Crank® revolutionary design makes every rotation extra smooth and ultra-efficient. It creates biomechanical flow that reduces stress on your body and your joints. This 2 in 1 cardio machine combines 2 exercise movements in 1 machine: 1. Zero impact Elliptical motion, and 2. The calorie blasting power of a Stepper. It gives you the smoothness of a flywheel spin bike, combined with the easy strides of an elliptical, and, the power generated from an upright stepper. Enjoy and experience effective total body workouts with synchronized upper body engagement for even better results with ZERO impact.This workout machine is an affordable alternative that puts you ahead of the curve.