For school beginners A great gift idea for school enrollment - minimalist, classic and perfect for the school bag! What is a calculation chain? Calculation chains are a popular accessory among elementary school students and preschoolers. When starting school, it is a practical tool for learning the number range from 0 to 20. It helps your child add or subtract numbers from each other. The beads are arranged in blocks of 5. Thanks to the key ring, the rake chain can be easily attached to a pencil case or school bag. material * 2 mm leather strap * Key ring 30 mm nickel free * 20 beads round 12mm silicone beads * 100% food grade silicone * BPA & pollutant free (certified), * Colourfast, saliva resistant, antibacterial and hypoallergenic.