What this connector is
The Amphenol FCI 87916-121HLF is the 21-circuit member of the BERGSTIK II unshrouded header series, a classic 0.100-inch (2.54 mm) pitch board-to-board interconnect with square male pins designed for through-hole soldering into a PCB. The single-row layout at this pitch is the original footprint standard that decades of legacy equipment still expects — it is the reason this position count exists as a discrete order code and not a custom cut.
Ratings that drive the fit decision
Push-pull fastening means the mating socket snaps and holds without jack-screws or locking tabs — acceptable for stable equipment interiors, but the unshrouded design has no anti-mis mate shoulder, so field techs should verify they are loading the correct socket before driving it home. The 0.830-inch post engagement length is long enough for multi-board stacking where the pin must survive several millimetres of flex during assembly.
Where it is used
The BERGSTIK II at this position count fills the board-to-board stacking and daughter-card interconnection role in industrial control modules, instrumentation front panels, and legacy automation equipment. The UL94 V-0 rating covers the flammability requirement for equipment safety certification in most industrial markets.