A modernist Scandinavian classic, Tonus by Kvadrat was conceived as a stretch upholstery textile to meet the demands of furniture designers' more challenging sculptural forms, and is best known as the upholstery standard popularly used on furniture icons such as Arne Jacobsen's Egg and Swan Chairs and Verner Panton's Cone Chair. Tonus was developed in collaboration with Nina Koppel (1942 1987), a teacher at the Danish School for Arts and Crafts and a designer known for her Georg Jensen jewelry.