From the "Birdsafe Naturals" Collection -- Birdsafe Naturals contain no dyes, no plastics, only safe natural wood and cotton rope. We do use stainless steel link , and you have the option for nickel or stainless steel chain for safely hanging toys since they can be heavy. The Birdsafe CottonWood is two strands of soft wood dangling on 1/2" cotton rope from a 2x4 (8" long). TWO POUNDS of safe, chewing fun!