ECR4Kids ACE Active Core Engagement Wobble Stool for Kids, Flexible Classroom and Home Seating, 20&rdquo;, Black Comfortable Wobble Chair - durable polypropylene stool allows rocking side to side and front to back for 360-degree movement, great for those who are restless, fidgety, ADHD, ADD or with special needs Ergonomic  improves posture by encouraging a balanced position with feet on the floor, helps strengthen and activate core muscles; arrives fully assembled Alternative Seating - durable stools are ideal for classrooms, schools, STEM environments, libraries, or homes with a non-slip seat and rubber base that prevents damage to floors Certified and Safe - GREENGUARD [GOLD] Certified for reducing chemical pollutants and helping improve the quality of indoor air ANSI/BIFMA  meets or exceeds the combined standards of both American National Standards Institute (ANSI) and BIFMA for safety, durability and structural adequacy in business and institutional furniture Product Dimensions  stool measures 13" L x 13" W x 20 H, 5.25 lbs Recommended for use by ages 12 years old and up; weight capacity of 250 lbs