The FCI 93939-124HLF is a 24-position, dual-row BergStik II unshrouded header on the standard 0.100" (2.54mm) square-pin grid. It's a through-hole, right-angle male pin header with 0.160" (4.06mm) mating pin length and 0.120" (3.05mm) solder-tail length, designed for board-to-board or wire-to-board interconnect where a robust, field-proven pin header is needed. The UL94 V-0 black thermoplastic housing and phosphor bronze contacts with 30.0µin (0.76µm) gold or GXT plating on the mating surface give it the mating cycle life and environmental resistance for production assemblies that see repeated mating.
That thickness is well into the field-grade range — not a thin flash that wears through after a few cycles. For a board-to-board header that might be mated and unmated during test, rework, or field service, that plating thickness buys you hundreds of cycles before the base phosphor bronze is exposed. The solder tails are tin-plated, which is standard for wave-solder compatibility and gives a good fillet. If you're specifying this for a high-vibration environment or corrosive atmosphere, the gold mating surface is the right call.
Comparison: 24 positions vs a 10-position sibling
Against a 10-position BergStik II header at the same 0.100" pitch, the 93939-124HLF carries 14 more circuits across the same dual-row footprint. The body length scales directly with position count — the 24-position version occupies about 2.4 inches of board edge, versus roughly 1.0 inch for the 10-position. The selection decision is purely about circuit count: match the header position count to your BOM line count. Everything else — pitch, current rating, plating, mounting — is identical across the series.