35 U.S.C. § 284 does not limit the compensation of lost sales to exclude a patentee’s patented device that is not covered by the patent in suit and directly competes with the infringing device if it is proven that those lost sales were caused by the infringement. Such lost sales are reasonably foreseeable and the award of damages is necessary to provide adequate compensation for infringement. However, if an unpatented device is sold to be used with the infringed device for purely marketing and business purposes, and not because they essentially functioned together, the patentee is not entitled to lost profits for the unpatented device.