Replacement Version 1 Tektro M300 Right Hand Brake Assembly with Waterproof Connector for the Rocky Road, Boulderado, Rubicon, Sedona, Baja, Catalina & Laguna 48 Volt Bikes. The Version 1 has a female plug end and male pin ends.
If you have the male plug end with a female pin end, you need the Version 2. Search site for part number 48VMTN-400R-2. If you have a beach cruiser, search part 48VBC-400R-2.