The Hirose DF12(3.5)50DP0.5V(80) is a 50-position header from the DF12 series, with outer shroud contacts arranged in two rows at a 0.020" (0.50mm) pitch. The header sits 0.110" (2.80mm) above the PCB surface after reflow. Board guide features and solder retention tabs are built into the body: the guide aids alignment when stacking two boards blind, and the retention tabs keep the part from shifting during SMT reflow.
Obsolete — plan the replacement before the BOM locks
Hirose lists the DF12(3.5)50DP0.5V(80) as obsolete. That means standard distribution stock is drying up and factory orders are no longer accepted. For a new design, you need a pin-compatible replacement from the current DF12 series — same 0.50 mm pitch, same 50 positions, same 3.5 mm stacking height.