We are developing an Acoustiguide programme that will include substantial outdoor segments. We intend to take credit card imprints as deposit, or cash of course, as security against theft. I understand that the Botanical Gardens in Melbourne, Australia, uses Acoustiguides for outdoor interpretation also - maybe you could contact them as well. Cheers, Greg McManus Director Rotorua Museum Te Whare Taonga O Te Arawa Government Gardens Rotorua New Zealand