What this connector is
The Amphenol FCI 87185-425HLF is the 25-circuit member of the BERGSTIK II unshrouded header family — a single-row, 0.100 inch (2.54 mm) pitch board-to-board header with tin-plated phosphor bronze contacts rated 5 A per circuit at 110 V. The push-pull fastening type means no threaded hardware; the header relies on contact normal force to stay mated, which works fine in stable equipment but isn't the right choice where vibration wants to pull the halves apart. The housing is UL94 V-0 black polyamide, and every one of the 25 positions is loaded.
Post length and board fit
The post length — 0.095 inch (2.41 mm) below the board — is the dimension that trips up field techs swapping this header on an existing card. The mating pin extends 1.043 inches (26.49 mm) from the insulator face, so the receptacle must be deep enough to accept that pin fully. Check your board stack-up against that 0.095 inch dress length before you commit — a thinner board will leave the post sticking through with nothing holding it, and a thicker board may bottom out the pin before the housing seats.
Tin plating at 100 microinches
The contact finish is 100 microinches (2.54 micrometres) of tin on both the mating face and the solder tail. That's a thick tin deposit — it holds up to multiple mating cycles better than thin tin, but it's still tin, not gold. If your application demands gold contacts for signal integrity or long fretting life, this isn't it. For power distribution or low-speed signal in a stable environment, tin at this thickness is solid and won't flake off the first time someone pulls the connector apart.
What it doesn't have
No shroud, no keying, single-row — that means no polarization on the header itself. Two of these headers will mate face-to-face with no alignment guidance, which is fine for test fixtures but a liability in production equipment where mis-mating costs you a whole board. If your system needs to guarantee correct orientation, you need either a keyed receptacle housing on the mating side or a different header with polarization features built in.