We got this as an addition to our 'regular' pee tray for our puppy. The mesh helps to reduce the tendency for accidental tracking since the pee flows down onto the pee pad beneath. It also prevents him from chewing up the pee pad. Do note that you'll want to regularly wash the mesh to avoid the odour accumulating from the pee (and poop, which can get caught in the mesh's openings). So there are trade-offs, but it's by no means a design flaw.