During his long association with Knoll he designed many important pieces of furniture including the "Grasshopper" lounge chair and ottoman (1946), the "Womb" chair and ottoman (1948), the "Womb" settee (1950), side and arm chairs (1948–1950), and his most famous "Tulip" or "Pedestal" group (1956), which featured side and arm chairs, dining, coffee and side tables, as well as a stool. All of these designs were highly successful except for the "Grasshopper" lounge chair, which, although in production through 1965, was not a big success.