This is the top tier of the position memory ladder. You see a near-full chess position with 17 to 24 pieces for 120 seconds, the board clears, and you reconstruct the whole thing from memory. It is a large step up from the intermediate drill (9 to 16 pieces): at this density you cannot hold every piece as a separate item, so the drill forces true chunking, storing pawn chains, castled structures, and piece clusters as single mental shapes.
This is the recall that separates casual players from titled ones. Masters do not have photographic memory, they recognize familiar structures and encode a whole position as a handful of chunks, which is why they can reconstruct a real game almost perfectly but do no better than anyone else on random piece placements. Two minutes is enough time to apply a system: fix the kings and queens first, then the pawn skeleton, then the minor pieces. Master this tier and holding a full board in your head during blindfold play becomes routine. New to the progression? Start with the base position memory drill or read the blindfold chess guide.