The idea for this design looks good on paper but in practice is a complete failure. The front side by the opening is wider than the other sides presumably to provide a wider surface for the cat to use as a step. Unfortunately this widened area doesn't go the full width of the front. This results is small alcoves in each front corner where the front returns to the normal plastic width. It is impossible to remove the lumped litter from these corners with a typical litter scoop. Failure to remove all the clumped, urine soaked, urine from these corners results in increased urine odour. Great idea of using the high sides but a complete failure to execute the cincept. A complete waste of time and money. 
Barrie