This are thin, low profile metal dies. Due to the nature of the product they are designed to be used in personal die cutting machines. Because of how these machines work (using rollers to achieve the pressure to cut) these dies can warp. It will not affect their performance. Thin, low profile dies are NOT designed to cut thick materials such as chipboard, wood, veneer, or plastics. They are designed and tested for use on paper, light fabrics, thin acetate, and some thinner felts. Please use them for their designed purpose and with the appropriate "sandwich" of plates/platforms for your machine per it's manual. Any other use on different materials/substrates will damage the dies, and quite possibly your machine. We are not liable for any damage to machines or materials due to use of our dies, as they are tested and approved for thin, low profile die use.