The extreme porosity enables a Graviti™ retaining wall to act as its own all-in-one drainage system, thereby avoiding the need for a separate drainage system and therefore saving time, money and materials in the construction process. Gravity Wall Systems is Australia’s premiere company for Graviti™ Concrete. Gravity Wall Systems Pty Ltd, PO Box 191, Ballina, NSW 2478, Ph: 02 6687 7465, Fax: 0414 382 921, Web: www.gravitywallsystems.com