If you're a manufacturer, and you want to showcase your product in a store that has a narrow but deep selection of merchandise and where expert sales associates can assist customers with their selections, you'd most likely choose a(n)
Based on the scenario being described within the question it can be said that for this you would most likely choose a specialty store. This refers to a retail business that focuses on very unique and specific product categories, in which everything revolves around that category. This category may be unique but offer a wide variety of product offering within it.
