A distribution tool (leveler) rakes or spins the grounds flat before tamping, so the puck extracts evenly. Like a tamper it is chosen by the basket's internal diameter and must match the machine's size. Some tools combine a distributor and a tamper in one adjustable body. It does not replace tamping — it evens the surface so the tamp lands flat.
New to sizing? See espresso portafilter sizes explained, or browse all part types.