What this connector is
The Amphenol FCI 87901-128HLF is the 28-circuit member of the BERGSTIK II series — a dual-row unshrouded board-to-board header rated 5 A per contact at up to 110 V. The push-pull push-pull fastening holds the mated pair without hardware, making it suited for internal board-stacking in equipment where the mating interface is seated once and left — not frequently reconnected in the field. Contacts are phosphor bronze with either gold or Gold GXT plating on the mating face at 30.0 µin (0.76 µm) thickness. That plating grade is what governs cycle life — the thicker the gold flash, the more reconnect cycles the contact survives before the finish degrades enough to affect contact resistance. Pitch is 0.100" (2.54 mm) with 0.100" row spacing; the square pin cross-section and 0.120" (3.05 mm) tail length are standard through-hole dimensions for this class. All 28 positions are loaded; the housing is black UL94 V-0 rated.
What the key ratings mean for fit
28 positions / dual-row at 0.100" (2.54 mm) pitch: this is the board-footprint driver. Confirm your board layout routing density and whether a 28-circuit header leaves adequate clearance for adjacent components. 5 A per circuit — this header is rated for power-duty contacts within the BERGSTIK II series, not just signal. The 110 V ceiling is the voltage limit; de-rate current if your operating temperature approaches the UL94 V-0 thermal ceiling of the housing material, not because of the contact itself. Push-pull push-pull fastening means no jack-screw hardware — the header relies on header-plug interference to hold the pair. That is acceptable for board-stacking in fixed assemblies; it is not suited for applications where the connector is repeatedly unmated under load or vibration without a secondary retention feature.