When it comes to describing businesses that specialize in certain products or services, there are a variety of synonyms that can be used in place of "deals in." For example, you might say a company "specializes in" or "focuses on" certain types of products or services. Alternatively, you could use phrases like "provides" or "offers" to describe what a business does. Other options include "sells," "supplies," "distributes," or "handles" specific types of goods or services. Ultimately, choosing the right synonym for "deals in" will depend on the context and tone of your writing, as well as the specific industry you are referring to.