a contract in which you agree to purchase all your requirements of a particular sort from one party

A form or contract that is used when the total long-term quantity required cannot be definitely fixed, but can be stated as an estimate or within maximum and minimum limits with deliveries on demand.

A contract for goods, services, or construction covering long-term requirements (usually twelve months or more), used when the total quantity required cannot be definitely fixed, but may be stated as an estimate or within maximum and minimum limits. Delivery of goods, services, or construction are made upon issuance of a delivery order. A requirements contract may be exclusive, in which case all orders of goods, services, or construction covered by the contract must be made pursuant to it during its term. In the alternative, a requirements contract may be non-exclusive, in which case the contract should be used whenever possible, but is not the only source of goods, services, or construction covered by it. Unless a requirements contract, and the solicitation for it, states that it is an exclusive contract, it is a non-exclusive contract. A requirements contract may not be used to unduly restrict competition and may not normally be used for large construction contracts.