The SK-1 made it possible to capture sounds from the surrounding environment, such as human vocals or sounds made by pets, to be processed further and used as timbres in musical performances. Making available the sampling function—which up until then had been the province of an extremely specialized subset of users and very expensive—to people throughout the world, this was a popular model that made Casio electronic keyboards familiar to more people around the world. The model sold over 1 million units.