Small brick is approximately 8"x4"x2", weighs about 1-1/2 lbs, and expands to  about 1/3 cubic foot of fluffy, organic potting medium.  For a small brick, add about 5 quarts of water, takes about 30 minutes to absorb. The picture on the cart shows 1 small brick expanded. NEW!  We now carry a 2 cubuc foot block (expanded) which wieghs about 11 lbs.