This is our flat sandbed 7 Hole Frag base rock by Ocean Aquaria!! Made in the United States, we use a special polymer resin filled with calcium carbonate making it very durable and weighted enough to be very stable in the sand!! This frag rock base offers 3 color options to enhance the look of your aquarium. It also provides a natural and stable environment for live coral and other aquatic organisms, promoting healthy growth and filtration in your tank. Designed specially for Reef Tank enthusiasts looking to update and "bling out" their aquascape!! measures 6"x4"x2" PLEASE SPECIFY WHICH COLOR YOU WOULD LIKE? CORALLINE PURPLE,BLACK, OR TAN!! THANK YOU!!