The Hirose DF12B(4.0)-60DP-0.5V(86) is a 60-position board-to-board header from the DF12 series, designed for mezzanine stacking applications where board real estate is tight. The 0.50mm pitch and 2-row layout pack 60 circuits into a compact footprint, with a mated stacking height of 4mm that suits low-profile parallel board connections.
What the 4mm stacking height means for your board stack
The 4mm mated stacking height is the dimension from the top of the bottom board to the bottom of the top board when mated. The 60 positions split across 2 rows means 30 contacts per row, so the connector footprint runs about 15mm long.