6907.21.10.05 - Tiles, whether or not rectangular, the largest surface area of which is capable of being enclosed in a square the side of which is less than 7 cm

This HTS classification covers unglazed ceramic flags and paving, hearth or wall tiles, where the water absorption by weight does not exceed 0.5%. These are typically dense, vitrified ceramic tiles that are either natural or formed into shapes and intended for use as flooring, paving, or wall coverings. The critical characteristic here is the low water absorption, indicating a high degree of vitrification and resistance to moisture and staining, often making them suitable for high-traffic areas or environments where water resistance is paramount.

Distinguishing this category from its sibling, "Other," implies that "Other" would encompass unglazed tiles with a water absorption coefficient exceeding 0.5%. Therefore, the key differentiator is the specific threshold of water absorption. This category is exclusive to tiles that have undergone a manufacturing process to achieve a very low porosity.

As this node is a leaf node, there are no further subcategories. Therefore, the focus for classification under 6907.21.10.05 is strictly on identifying unglazed ceramic tiles that meet the specified water absorption criteria. Examples would include porcelain tiles that are not glazed and exhibit very low water absorption, as well as certain types of dense ceramic tiles designed for industrial or heavy-duty applications where their impermeability is a defining feature.