These extra large building blocks promote creativity, logic and reasoning skills as well as developing motor skills and hand and eye coordination. Blocks interlock securely and encourage children to work and communicate together. Gorilla BlocksTM foam evolved from automotive safety applications, and is extremely durable, non-toxic, weatherproof and recyclable. Set includes 66 pieces in assorted sizes and colors. The entire set weighs only 8 lbs., but each individual block can hold up to 220 lbs. of weight.