We recommend a maximum of 4 packed Perfect Crates be stacked on a Rental Skate or a Rental Dolly. Although, some users have reported moving packed Perfect Crates in higher stacks, professional movers who move for a living, believe 4 packed Perfect Crates is a manageable number to roll using either of our rental dollies. However, once the packed Perfect Crates are inside the moving truck and not stacked on the Rental Skate or Rental Dolly, the Perfect Crates are designed to stack as high as the interior height of the moving truck will allow.