1.5mm organic plant dyed pure wool felt. The organic felt carries the Bioland Certificate. The certication also covers EN 71 standard for the felt as well as the colours used in the dyeing process. For more information about what the Bioland Certificate entails please click on this link http://www.bioland.de/fileadmin/dateien/HP_Dokumente/Richtlinien/2013-11-26_Bioland-Standards.pdf