S = Flat-style Crayons M = Building Block-style Crayons. This set contains 20 stackable crayons, each featuring 12 distinct colors-an ample quantity sufficient to meet daily usage needs or for sharing. Each crayon measures 25.5 cm in total length and is composed of multiple detachable 3.4 cm segments, allowing the length to be adjusted as desired. Crafted from paraffin wax and plastic, the product is of reliable quality, odorless, and resistant to fading. Its modular, stackable design allows users the freedom to combine the pieces and create a wide variety of shapes. It is ideally suited as an educational aid, helping to foster children's color recognition, hand-eye coordination, manual dexterity, as well as their imagination and creativity. Weight: 0.638 lbs.