Receive one regular (60 x 40cm) delivered to your door. When the your Paw-ta-Potty arrives simply put it on the floor where you want your pet to toilet. Once the grass starts to die the grass can go into general or green waste and the carton into the recycling, simple as that! Most pets don't need training, they instinctively want to use it.
The grass will absorb the urine through the root systems as if it were water, you still need to collect the poo (bugger I know!).