When you ride on the road, you'll use your torso and arms to balance and steer. While most trainers take these efforts away from you, Kinetic by Kurt's Rock And Roll Trainer mimics these natural movements. When you add this Kinetic Turntable Riser Ring, you're forced to work those same upper body muscles to keep the front wheel in alignment with the frame. This is part of the "road feel" equation and you'll appreciate it when you're sprinting and standing. The Turntable Riser Ring is a PVC circle that has slots of four different heights. The four heights range from 1/2in to 2in from the floor. All can accommodate a tire up to 2. 25in in width. The ring sits atop a "Lazy Susan" style turntable that swivels freely. The Kinetic by Kurt Turntable Riser Ring is Black and is 9in in diameter. It can be used with other trainers, though the swiveling benefit of using the turntable ring with fixed-style trainers is negligible.