A buyer may reject a seller’s attempt to cure a nonconforming installment if the defect substantially impairs the value of the installment. The nature of a buyer’s right to reject nonconforming goods depends on whether the contract is a single-delivery contract or an installment contract. Single-delivery contracts are governed by a modified version of the perfect-tender rule under UCC § 2-601. This means, generally, goods delivered under a single-delivery contracts must match the contract specifications very closely or else the buyer can lawfully reject the goods. In contrast, in an installment contract, UCC § 2-612 only makes the seller provide goods that are substantially like the goods ordered, not exactly like the goods ordered. This means, under an installment contract, a buyer can reject a particular nonconforming installment only if the defect substantially impairs the value of the installment. The seller also has an opportunity to cure the defect within a reasonable amount of time. Additionally, delivery of nonconforming goods in an installment contract allows a buyer to cancel the entire contract only if the defect impairs the value of the entire contract.