In America, a series of cars was developed from at first cast metal and later styrene models ("promos") offered at new-car dealerships to drum up interest. The firm Monogram, and later Tamiya, first produced them in a scale derived from the Architect's scale: 1:24 scale, while the firms AMT, Jo-Han, and Revell chose the scale of 1:25. Monogram later switched to this scale after the firm was purchased by Revell. Some cars are also made in 1:32 scale, and rolling toys are often made on the scale 1:64 scale. Chinese die-cast manufacturers have introduced 1/72 scale into their range. The smaller scales are usually die-cast cars and not the in the class as model cars. Except in rare occasions, Johnny Lightning and Ertl-made die-cast cars were sold as kits for buyers to assemble. Model cars are also used in car design.