Electronic commerce (e-commerce) covers a wide range of business transactions. Usually, a transactions includes products, i.e. goods or services. Often, e-commerce websites are intended to offer a large variety of products, most of which are not fully recognized at the time when the system is constructed. Nevertheless, there is need to describe these products in an elaborated way in order to support prospective customers in finding adequate products. Since new product types may have to be registered on a daily basis, changing a data base schema or program code is no satisfactory option. Instead there is the need to register new product types during the run time of a system. In addition, the representation of product variants and the construction of individual product configurations should be possible. Current approaches to represent products do not fulfill these requirements to a satisfactory degree. The design of appropriate conceptual models requires to thoroughly differentiate between various levels of abstraction. This includes decisions to be made between instantiation, specialization and ”uses” relationships. Against this background, the paper presents three prototypical design alternatives for versatile product representations. They vary in terms of flexibility, reusability and ease of use. The work presented in this paper resulted from the design of a reference model for e-commerce platforms.