<p>Litter-Robot 4 features the all-new SmartScale® that lets you monitor kitty’s activity and weight through the Whisker app. If your Litter-Robot 4 sits on carpet (or you plan to use it on carpet), you can improve the accuracy of SmartScale® weight readings by placing our specially designed carpet tray between the unit and the floor.</p> <ul> <li>Recommended for use on carpet or uneven flooring</li> <li>Easy to install (no tools required)</li> <li>Easy to clean</li> </ul>