A rare 1930s prototype Leica camera fitted with a rifle stock is expected to sell for over $330,000 when it is auctioned off in Vienna, Austria, on Saturday.

The New York Leica Gun Rifle was built by Leica’s predecessor company Ernst Leitz circa 1937.  Auction house Westlicht Photographica describes the camera as “one of the most rare and unusual treasures in the history of photography.”

Bidding for the camera will start at $169,000, with final bids expected to be between $337,000 and $393,000, according to Westlicht Photographica.

Only between 10 and 12 of the prototype cameras are thought to be in existence, CNET reports, noting that the gadgets were favored by wildlife and sports photographers in the inter-war years.

Notable features of the camera include a special bayonet mount viewfinder and a modified baseplate for the rifle stock.