The Stokke Baby rail Innovative new attachment for the Tripp Trapp allows babies as young as 6 mos. to sit and enjoy meals with the family. Ages 6 to 24 mos. The plastic material used in the Stokke Tripp Trapp Baby Rail is the most environmentally-friendly available. It can be recycled and contains no hazardous materials for children to touch or bite/chew on. The Tripp Trapp Baby Rail can only be used on the Tripp Trapp chair. It will not fit on a Stokke Kinderzeat