Ultra-Fab Products 48-979051 - Ultra Leveling Blocks Interlocking blocks are stackable in a number of configurations. Interlocking blocks are stackable in a number of configurations. Stack in different ways to achieve a perfect leveling of your RV. Blocks measure 8.3125" x 8.3125" with a 30,000 lb weight capacity Comes with a handy carrying/storage bag 10/pack Manufactures 3-Year Warranty