DF40GL-44DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch board-to-board mezzanine receptacle designed for compact electronic assemblies that need reliable interconnect performance in limited PCB space. As part of the DF40GL series, it suits portable devices, industrial control modules, communication equipment, embedded systems, and other multilayer board architectures where 0.40 mm pitch and 1.5 mm mated stacking height support dense packaging. Engineers typically choose this connector for its surface-mount format, shielded construction, gold contact finish, and solder retention features, which help support assembly stability and signal integrity in compact designs. The listed part status is Active, which is favorable for ongoing design consideration, although the broader lifecycle status provided here is unknown and should still be verified through official manufacturer channels before volume commitment. RoHS compliance information is not available in the provided data, so environmental compliance should be confirmed using current Hirose documentation or authorized supplier records.