This is an Aria brake for a tandem:
Arai Drum Brake Tandem Touring Bicycle Bike Drag | eBay

Please note that Aria is a Japanese company that has made dozens of different drum brakes for bicycle and similar applications - only one model was intended to be a drag brake for tandems. Contrary to reiker's opinion, the tandem drag brake is amoung the least common Aria produced for the world market, which is why the price is high, and it is no longer made.

Also, please note that Arai drag brakes were almost always optional, not standard equipment on tandems.

Take a look at these options:
http://www.sjscycles.co.uk/brakes-ta...pt603/?geoc=us

Karasawa is currently the worlds's highest volume manufacturer of drum brakes for bicycles; and $88.63 including shipping to the USA is not much to risk....
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