Heavy-Duty Rubber with Adjustable Height: 3 Adjustable heights for customized workouts. Ideal for achieving deeper squats, gentle physical therapy stretches, or targeted calf raises, all backed by ultra-grip rubber to prevent slips Protect Knees, Lift Heavier: Incline promotes knees-over-toes alignment, reducing joint strain. Dense rubber core stabilizes squats on grass/concreteideal for heavy weights or outdoor workouts