Hosspad Extreme - Stabilizing , Jacking & Leveling Pads (4 Pads Per Pack) Can be used on Any Surface (Grass, Gravel, Cement, Asphalt, Dirt) Protects and Can Replace Plastic RV Jack Blocks Outlasts Plastic , Wood , Bricks Resistant to Water, Oil, UV Light, Corrosion, Salt Resistant to cracking, splitting, chipping, breaking