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