The Hirose DF12NB(3.5)-50DP-0.5V(51) is a 50-position board-to-board mezzanine header from the DF12 series, with outer shroud contacts that protect the pins during handling and mating.
The 0.020" (0.50mm) pitch governs the PCB footprint — the board layout engineer needs to route traces between pads at this density, which typically requires at least a 4-layer board for signal escape.
Position Count and Stack Height Options
If the board-to-board gap is tighter, the DF12NB(3.0)-50DP-0.5V(51) offers the same 50 positions but at a 2.30mm mated stack height instead of 3.5mm, which changes the z-height budget and may require a different receptacle.