The Camco 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 stack height. Camco’s FasTen Leveling Blocks can be used with single wheels, double wheels, hydraulic jacks, tongue jacks, stabilizer jacks, 5th wheel jacks, and tandem axles. The convenient carrying handles easily pulls up for carrying or twists down to secure blocks together for storage. Product dimensions: 8.5” x 8.5” x 1”. Stack height should not exceed 4-1/2 inches.