The “Apache” was a combination knife, brass knuckles, and revolver made by several companies in Belgium and France, which became associated with a group of street thugs in Paris around the turn of the century. They were patented by a man named Louis Dolne and made in a variety of different styles, but all share the same basic mechanical features. One common misconception, I believe, is the idea that the folding blade was to be used in conjunction with the revolver. This makes basically no sense, but the blade would have had some utility if used with the brass knuckles.
This particular one is paired with a Belgian pinfire pepperbox, and available for sale at Rock Island on Friday the 20th.