Camco’s FasTen Leveling Blocks allow you to stack the interlocking blocks to the desired height for safe and easy leveling. Each block adds a full inch to the stack height. These blocks can be used with single wheels, double wheels, hydraulic jacks, tongue jacks, stabilizer jacks, 5th wheel jacks, or tandem axles. Made from UV stabilized resin, they are built to last even with extended exposure to sunlight. They are engineered with a patent-pending design to optimize both strength and weight. The convenient carrying handle easily pulls up for carrying, or twists down to secure blocks together for storage.