What is the Sustainably Sourced Knit version made from and does it have any harmful materials?

The Sustainably Sourced Knit version is made with 100% Tencel™ Lyocell fibers. As with all Ergobaby products, the materials used in production are carefully sourced and thoroughly tested to be free of potentially harmful substances. You can get more information here. (link to 'harsh chemical' article in Safety and Compliance)