The Mini-Wright Standard is calibrated by hand, to ensure that readings from any two meters are comparable. This enables a patient to use a Mini-Wright at home, and use a different Mini-Wright at the Clinic, yet still rely on the readings obtained. Mini-Wright peak flow meters also have a built-in one-way valve - an individual is prevented from inhaling through the device. This reduces the risk from others who have previously used the meter. It also facilitates the use of inexpensive cardboard tubes as disposable mouthpieces. Mini-Wrights are constructed from medical grade materials - they can be cleaned easily by agitation in mild detergent, rinsing, and allowing to dry completely. Individually calibrated. Built-in one-way valve. Suitable for most older children and adults. 60-800 Litres per minute measuring range. Durable construction for years of reliable performance. Supplied complete with instructions for use, patient self-monitoring chart and sterilisable universal mouthpiece.