The Denver block has. a rear lip system that allows for fast installation also feature a hollow core design that helps with drainage and connection between the unit when the cells are properly filled with multipurpose gravel. Color blending may vary sienna is a blend of tan Brown and charcoal resulting in natural variations in color. Width 17" depth 12" and height 6". Regular price at Menards is $5.79. after rebate price drops seen as low as $4.79.   We have 40 blocks available. $3.50 each.