Flex, an under-examined element of surf design, is discussed by seven maestros of flex, none of them interested in a stiff sled. Renny Yater, Mitchell Rae, Shawn Ambrose, Sage Joske, Timmy Patterson, Steve Pendarvis, and Bert Berger each discuss their approach to incorporating flex into a board, through the use of different materials (e.g., foam, resin, glass, wood) and techniques (e.g., rails, stringers, tails, decks).