McKenzie Artificial Ledge Rock Bases   Artificial urethane rock ledge bases - the most versatile rocks ever made! The urethane rocks are created from a semi-flexible urethane, reinforced with wood making them strong yet very light. The Original rocks are created from the original material that is strong, resists chipping and is stable. Both have the same shape and texture. Oatey Putty is our recommended epoxy for securing forms to artificial rocks. View: How To Measure Rocks A broad selection of informative How To Instructions and free videos are available online. Technical support has always been an integral part of McKenzie Customer Service - our technical staff is available Monday - Friday, 8 AM - 5 PM Eastern Time at 1-800-279-7985 for any questions.