The closed end means this receptacle terminates the end of a wire run, not a pass-through daisy chain.
Termination and Plating — What Matters in the Field
Termination is IDC — the contacts pierce the wire insulation as the cover is pressed down, no crimp tool needed. That makes it fast for repetitive harness builds, but the connection is permanent: once terminated, you don't rework it. The tin plating at 80.0 µ" (2.03 µm) is thick enough for a reliable gas-tight joint in indoor environments; tin is fine for limited mating cycles (a few dozen at most) and holds up in dry, temperature-controlled gear. If the harness sees frequent disconnect or corrosive fumes, gold-plated MTA-100 variants exist — but for a one-and-done wire-to-board run, this tin contact does the job.