Mesh prevents tampering of sheets from ripping or removing them. Safe even for naughty dogs. Rounded mesh corners to reduce snagging.The shape makes it difficult for nails to enter and urine to pass through. You can unlock the sheets from both trays so you can change and clean your sheets! The mesh cover can be removed, so you can use it as a normal toilet tray when you are done with it. Non-skid feet on bottom