At 0.50 mm pitch across two rows, it packs the full 80 positions into a compact body — the board footprint stays narrow, but the trace routing between pads demands careful clearance for a 0.50 mm pitch.
The 4.5 mm mated stack height is a single fixed value, not a range; the mechanical enclosure must allocate exactly that z-height plus clearance for the receptacle body. Dual-row arrangement at this pitch gives a 20 mm body length for 80 circuits, which fits high-density mezzanine designs but leaves little room for fan-out on inner layers.
The 80 positions match the BOM line count. The 0.50 mm pitch drives the board footprint. The 4.5 mm stack height is the only option in this mated pair.