If you want to plug your National Luna fridge into an accessory port like exists in modern vehicles, or the 12v port on a portable battery like an , you'll need this cord.

National Luna fridges come with a hella-style plug that while very efficient at energy transfer, are not compatible with an accessory port.

The fridge does come with a hella socket that can be wired into your vehicle, so if you plan on using that or are going to hard wire the fridge to your battery or a fuse block, this cord is not needed.