A flying disc is a disc-shaped glider that is generally plastic and roughly 20 to 25 cm (7.9 to 9.8 in) in. diameter, with a lip. The shape of the disc, an airfoil in cross-section, allows it to fly by generating lift as it moves through the air while spinning. The term frisbee, often used uncapitalized to generically describe all flying discs, is a registered trademark of the Wham-O toy company. Though such use is not encouraged by the company, the common use of the name as a generic term has put the trademark in jeopardy. Flying discs are thrown and caught for free-form recreation and as part of many different flying disc games. A wide range of flying-disc variants are available commercially. Disc golf discs are usually smaller but denser and tailored for particular flight profiles to increase/decrease stability and distance. Disc dog sports use relatively slow flying discs made of more pliable material to better resist a dog's bite and prevent injury to the dog.