I apologize for cross-postings... I am wondering if anyone has had experience with providing audio tours such that the users are free to roam in unsupervised areas, such as out-of-doors, where the visitor has the opportunity to walk away without returning the unit. Is this done anywhere? If so, how did you ensure that the units would be returned? Was it effective? Thank you for your input! -Kelly @@@@@@@@@@@@@@@@@@@@@@@@@@@ Kelly Ray Research Assistant Challenger Center for Space Science Education 1029 North Royal Street, Suite 300 Alexandria, VA 22314 phone: 703/683-9740 fax: 703/683-7546 e-mail: [log in to unmask]