Specially designed Rock Planting Slab for bonsai. Designed by Bonsai Boy and made by a top artificial rock manufacturer. Our rock slabs are made of a commercial grade GFRC (glass fiber reinforced concrete) mixture and features two built in drainage holes with a raised lip around the planting area and of course, all the look and feel of a real rock.  15" x 8" x 1" 2 drainage holes Raised lip around planting area 5 lbs