To have a textile or leather product certified by Oeko-Tex, manufacturers must supply samples of all components (including accessories like buttons, zips, studs, sewing threads, labels or prints) for analysis to a laboratory at one of the Oeko-Tex member institutes. The Oeko-Tex certificate is issued after successful testing of the materials for compliance with the Oeko-Tex standards and the signing of a declaration of conformity. Part of the certification process is also a company audit at the certified item's production facility, conducted shortly prior or after the issuing of the certificate. Later on, audits take place at least every three years.