3-in-1 High Density Foam Plyo Box + PVC Cover3 in 1 High Density Foam Plyo Box + PVC Cover The Fitness Hero 3 in 1 High Density Foam Plyo Box is engineered specifically with safety and functionality in mind. Our plyo box is multi layered and designed for workouts that involve jumping, bounding, stepping, splitting and more. By using this stable platform for a single or double leg and arm cardio movements, it can easily enhance your bodyweight workout into a serious and intense sweat session.