The orange housing and closed-end design help orient the connector in a harness build — the colour signals the wire gauge or circuit group on the line.
IDC Termination and Wire Fit
The 18 AWG gauge is the only wire size the slot is designed for; a different gauge will not seat correctly or may damage the contact beam. The IDC joint is gas-tight on solid or stranded wire, but the MTA-156 series is built for mass-termination on a harness board, not for field rework. Once the wire is in, it stays.
The plug mates with the matching MTA-156 receptacle header (through-hole or vertical mount). The free-hanging or right-angle mounting option means the plug can sit inline with the cable or exit at 90° to the board edge — useful when the harness routes tight against the enclosure wall. The closed-end feature blocks the last position, preventing a mis-seat or a stray pin from passing through.