The 280521-2: The 3-wall shroud and detent lock keep the plug aligned during mating and resist vibration loosening — useful in equipment where the connector sees occasional movement or service access. Gold plating on the mating pins (15.0µin) supports repeated connect/disconnect cycles without contact fretting, while the tin-plated solder tails keep the board-side cost in check.
In a 24-position fully loaded connector, the total current per row is 36A, but the board trace and receptacle rating will set the real limit.
The square pin profile (0.025" square typical for AMPMODU) accepts standard crimp-socket or IDC receptacles from the same series.