Shinwoo is a South Korean yo-yo manufacturer that first began making yo-yos in 1987. Shinwoo yo-yos are sold internationally with some models appearing in U.S. online retailers. Outside of the United States, some yo-yos are sold with a counterweight, which is not permissible in the U.S. due to the Steve Brown's patent on 5A (freehand) play which is licensed to and managed by Duncan Toys.