Stacka Levels are extremely strong and robust levelling blocks, that interlock with each other. This enables the blocks to be built up to the required height for levelling. High-Quality, safe, and effective tire blocks for leveling your camper, RV or Trailer. 6 ton weight limit. 13.5 in. x 9 in. x 2 in. Unique interlocking pattern allows them to be turned sideways for more stability.