All of our bolsters use shells that are made of pure 100% mulberry silk, 25 momme, grade 6A, and Oeko-Tex Certified standard 100 (This latter point emphasizes that the dyes used in our silk are free of harmful chemicals). Proper filler choice is a key component in providing comfort; therefore, we carefully pick filler that is hypoallergenic, made in the U.S.A., and has discrete shapes to ensure that the filler for your pillows and bolsters will distribute evenly and resist clumping.