A childrenswear set consisting of a pair of trousers and a pullover from the Petit Pli 'clothes that grow range'. Made from recycled polyethylene terephthalate (PET) bottles, with no other fibres included within the fabric to enable more easy recycling at end of life. The smart, technical fabric is folded, inspired by origami principles, to expand along both its width and length when stretched, possessing an embedded auxetic structure with a negative Poisson's ratio. To reset, the material is simply pulled along the horizontal. In this way the clothes are capable of expanding through seven different sizes, designed to fit a child from 9 months to 4 years, and thus reducing the need to buy additional clothing. The arms and legs have adjustment tabs and silicone grippers to maintain fit and the pleats point downwards to avoid the collection of crumbs and spilled liquids. The fabric is breathable, waterproof, lightweight, reinforced for additional strength with reflective strips for visibility. Winner of the James Dyson Award in 2017, the Dezeen Award for Best Wearable Design in 2018 and the H&M Global Change Award, Fast Company's 100 World Changing Ideas and the Red Dot Product Design Award in 2019. Measurements are provided for the trousers in their smallest size.