Barker (P) was injured at a construction site while operating a high-lift loader manufactured by Lull Engineering Co. (D), and leased to P's employer by George M. Philpott Co. (D). The loader was designed to lift loads of up to 5,000 pounds to a maximum height of 32 feet. The loader is 23 feet long, 8 feet wide and weighs 17,050 pounds. The loader was not equipped with seat belts or a roll bar. A wire and pipe cage over the driver's seat afforded the driver some protection from falling objects. The cab of the loader was located at least nine feet behind the lifting forks. The accident occurred while plaintiff was attempting to lift a load of lumber to a height of approximately 18 to 20 feet and to place the load on the second story of a building under construction. The lift was a particularly difficult one because the terrain on which the loader rested sloped sharply in several directions. When it appeared to several coworkers that the load was beginning to tip, the workers shouted to P to jump from the loader. P heeded these warnings and leaped from the loader, but while scrambling away, he was struck by a piece of falling lumber and suffered serious injury. P sued D in tort to recover damages for his injuries. P claimed that his injuries were proximately caused by the defective design of the loader. By reason of its relatively narrow base, the loader was unstable and had a tendency to roll over when lifting loads to considerable heights. The expert additionally testified that the loader was defective in that it was not equipped with a roll bar or seat belts. Witnesses suggested that the accident may have been caused by the defective design of the loader's leveling mechanism. Ds' experts testified that the loader was not unstable when utilized on the terrain for which it was intended, and that if the accident did occur because of the tipping of the loader it was only because P had misused the equipment by operating it on steep terrain for which the loader was unsuited. D's experts further testified that a roll bar was unnecessary because in view of the bulk of the loader it would not roll completely over. Witnesses also maintained that seat belts would have increased the danger of the loader by impairing the operator's ability to leave the vehicle quickly in case of an emergency. The jury found for D. P appealed, claiming that the trial court erred in instructing the jury 'that strict liability for a defect in design of a product is based on a finding that the product was unreasonably dangerous for its intended use.'