I have found this A-903 rust eraser from Naniwa really handy when restoring razors. It has a texture similar to a pencil eraser but it contains aluminium particles and is designed for easy rust removal. It is slightly flexible and the particles run through the entire block so it will keep working as the block is worn away.
It does leave fine scratch marks because ultimately it is removing rust through abrasion, but nevertheless the particles in the eraser are small and I have found it really useful. Clearly it can potentially be used for rust removal on many other items including kitchen knives, pans, stoves, tools, skis and other items.
These erasers are grey which seems to have replaced the pink of earlier blocks.
Size: 50 x 40 x 20 mm
Material: fused alumina polyvinyl chloride