Many large format tiles, especially porcelain are inherently bowed, the less expensive tiles are more severely bowed. We use lippage systems to compensate and reduce lippage to a minimum. The TCA lippage tolerance is 1mm or 1/32” or the thickness of a dime, we strive for zero but are limited to the tile quality. We use either the system shown, wedges or spin type depending on the installation. Some refer to these as leveling clips, they do not make a wall or floor level.