In 1933, canvas footwear pioneer BF Goodrich patented the Posture Foundation insole, and began adding the new technology to its action shoes. Goodrich shoes with Posture Foundation became known simply as "P-F" in 1937. Fashion trends in the Forties and Fifties saw PF Flyers expand from gyms and ball fields to become fashionable active footwear. "Everything you do is more fun with PF" read one 1947 magazine ad. PF styles ranged from high- and low-top sport shoes to oxfords and moccasins "for work, relaxation and play." By the 1960s, PF was one of the most popular shoes in America.