Your Garryflex block is a multi-purpose abrasive cleaner impregnated throughout with sharp abrasive grit.
Use on iron, steel, aluminium, plastics, ceramics, paintwork, etc.
For finer results the Garryflex block can be used with water, washing up liquid, white spirit, paraffin, etc.
Used in industry by sheet metal workers, stainless steel fabricators and in the metal finishing trades or handy for model railway track cleaning, just to name a few uses.