Vertical linking is the practice of requiring customers to purchase related products or services together from the same company.  For example, a company could require that its automobiles be serviced only by its own dealers. To limit this problem, many jurisdictions require that warranties not be voided by external maintenance. See e.B. the Magnuson-moss Warranty Act in the United States. Seams (informal, product-related) are the practice of selling a product or service as a mandatory supplement to the purchase of another product or service. From a legal point of view, a binding sale makes the sale of an item (the binding goods) dependent on the de facto customer (or de jure customer) on the purchase of a second distinctive item (the linked item). Adhesion is often illegal if the products are not naturally bound. It is related, but different from free marketing, to a common (and legal) way to give away an item (or sell it at a significant discount) to ensure a continuous flow of selling another related item. User contracts are subject to unfair competition law. Such agreements tend to restrict competition by forcing buyers to buy inferior goods they don`t want or more expensive goods they could buy elsewhere for less. In addition, competitors can lower their prices below market levels to keep buyers away from possible binding agreements.
Competitors who sell their products below the market price for an extended period of time can suffer huge losses or go bankrupt. Such practices are prohibited under Article 101(1)(e) and Article 102(2)(d) and may constitute a breach of the law if other conditions are met. It should be noted, however, that the Court is prepared to find an infringement which goes beyond the infringements listed in Article 102(2)(d) (see Tetra Pak v Commission).  Horizontal grouping consists of requiring consumers to pay for an unrelated product or service at the same time as the desired product or service.  A hypothetical example would be that Bic sells its pens only with Bic lighters. (However, a company may offer a limited free item with a different purchase as a promotion.) Certain types of installations, in particular contractual ones, have been considered anti-competitive practices in the past. The basic idea is that consumers are harmed by being forced to buy an unwanted good (the tied good) in order to buy a good they really want (the constraining good), and therefore prefer to be sold separately. .