In the late 1960s, Elliot Handler, co-founder of Mattel, developed the concept for Hot Wheels as a toy line that would appeal to boys in the same way their Barbie had to girls.[2] Handler was inspired to create a new line of toy cars after seeing his son Kenneth play with Matchbox cars. Unlike Matchbox, which focused on small-scale models of real production vehicles, Handler envisioned Hot Wheels as a line of exaggerated, customized "hot rod" cars, featuring big rear tires, superchargers, flame paint jobs, hood blowers, and outlandish proportions.[citation needed] He began producing the cars with assistance from fellow engineer Jack Ryan.[3] The flame logo was designed by artist Rick Irons, who worked at Mattel at the time.[4] Mattel first unveiled 16 Hot Wheels cars in the 1968 New York Toy Fair.[5] The Sweet 16 The first line of Hot Wheels cars, known as The Original Sweet 16 were manufactured in 1967. These were the first of the Red Line Series, named for the tires which had a red pin stripe on their sides.[6][failed verification] There were sixteen castings released, eleven of them designed by Harry Bentley Bradley with assistance from Handler and Ryan.[7][dead link] The first one produced was a dark blue "Custom Camaro".[8] Bradley was from the car industry and had designed the body for the (full-sized) Dodge Deora concept car and the Custom Fleet side, (based on his own customized 1966 El Camino).