What is the meaning of the p printed on abrasive papers?

The "P" printed on abrasive papers stands for "P-grade," which indicates the paper's grit size according to a specific grading system established by the Federation of European Producers of Abrasives (FEPA). This system categorizes abrasives based on the size of the particles used, where a higher "P" number corresponds to finer grits. For example, P120 indicates a coarser grit, while P400 signifies a much finer abrasive. This standardization helps users select the appropriate abrasive for their specific sanding or polishing tasks.