The practice of supplying distributors with goods only on the condition that they carry the full range of a firm’s products. This may be used as a monopoly device: for example, if some car spares are highly specific to a make, while others are generic products available more cheaply from rival suppliers, full line forcing protects the manufacturers from being undercut on the spares other people can make as well. Manufacturers defend full line forcing on the grounds that they need to protect their reputations with customers who may not appreciate that spares they are being sold by others are inferior substitutes.