The Amphenol FCI 79821-404HLF is a 4-position, dual-row BERGSTIK® II unshrouded header on the standard 0.100" (2.54 mm) pitch. It's a through-hole solder type with square male pins, push-pull mating, and a black UL94 V-0 rated insulator. Typical use is as a board-to-board interconnect — think signal or low-current power links between PCBs where you need a simple, reliable pin header.
The 0.100" (2.54 mm) pitch is the classic breadboard and perfboard spacing — any board layout engineer will recognize the footprint immediately. 4 positions in 2 rows means a 2x2 grid; the row spacing is also 0.100" (2.54 mm), so the pin pattern is a clean square. That's the real limit — the tin surface, not the current rating, governs where this part belongs.