How are two cobblers who control the shoe making business an oligopoly?

Two cobblers who control the shoe making business could be an oligopoly in a situation with the following conditions:

- a small number of firms (two or more) have full (or most) control of an industry

- options such as price and/or output amount depends on the other firm offering the service in the industry.

- barriers to entry enabling market share between the firms

- differentiated products/services including effective advertising and quality products/services.