The first commercial 707s, labeled the 707-120 series, had a larger cabin and other improvements compared to the prototype. Powered by early Pratt & Whitney turbojet engines, these initial 707s had range capability that was barely sufficient for the Atlantic Ocean. Boeing quickly developed the larger 707-320 Intercontinental series (shown here) with a longer fuselage, bigger wing and higher-powered engines. With these improvements, which allowed increased fuel capacity from 15,000 gallons to more than 23,000 gallons, the 707 had truly intercontinental range of over 4,000 miles in a 141-seat (mixed class) seating configuration.