DF40B-50DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch board-to-board rectangular connector designed for compact electronic assemblies that need reliable mezzanine interconnection in limited space. As part of the DF40 series, this 50-position, 0.40 mm pitch receptacle is well suited for portable devices, industrial control modules, embedded computing boards, medical electronics, and other dense PCB designs where low profile and consistent mating performance matter. Features such as gold contact finish and solder retention support stable assembly and long-term connection reliability in automated production environments. The listed product status is Active, which is favorable for current designs, although lifecycle planning should still be verified through official manufacturer channels. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance status should be treated as information not available pending confirmation from Hirose documentation or an authorized distributor. For procurement teams, the tape-and-reel packaging and standard 5,000-piece packaging support scalable production sourcing.