Check out the site DalaiTom posted. This is the sea bed rock quarried in Florida we used. Check the pictures of base rock and compare it to the pictures of holey rock. I am prejudiced, but there is no comparison. The holey rock is much denser and does not have near the surface area of referrocks' base rock. If they are doing business as they were when we ordered, they will take a picture of your order, if you rerquest one, and you will see what you are ordering. We did, and the original picture had smaller rock then what we wanted, so they picked some bigger rock for us. The final order was approximately 25% more then then the weight we ordered, and at no additional charge. Can't say enough good things about this base rock.