DF40GB-30DP-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board connector designed for compact, high-density electronic assemblies. As part of the DF40 series, it targets space-constrained products that need reliable mezzanine interconnection, including portable medical devices, industrial control modules, communication equipment, and compact embedded systems. Its 0.40 mm pitch, 30-position layout, surface-mount format, and shielded construction make it well suited for designs where signal integrity, mechanical retention, and reduced board area are important. The part is listed as Active in the provided specifications, which is a positive indicator for ongoing design support, although engineers should still confirm long-term availability with Hirose or authorized channel partners. RoHS compliance information is not explicitly provided in the supplied data, so formal compliance status is best treated as information not available pending manufacturer documentation. For new procurement or qualification, engineers should verify the latest datasheet, compliance declaration, and packing details before release to production.