The AirZone is the product of two years of research and development by Clement Clarke, the world's most experienced peak flow meter manufacturer. A leading manufacturer of respiratory devices for over thirty years, Clement Clarke have designed a personal peak flow meter around the needs of both patient and professional. Accuracy, reliability, portability and simplicity, all at a price that's affordable. Featuring a special tamper-proof zoning system that makes the most of self-management plans, the AirZone is suitable for both adults and children. The folding handle adds to its convenient design, allowing it to be with you when you need it. In keeping with the highest of manufacturing practices, every AirZone is hand calibrated. It easily exceeds both the United States Standards and the Australia/New Zealand Standards for peak flow meters