Probe Covers for the Welch Allyn Thermoscan. To assure accuracy and sanitary practice, change or clean lens filters after each use. Fits all Braun ThermoScan models. The Braun ThermoScan Lens Filters are safe, hygienic and comfortable to use with children and adults. Just attach clean lens filter to the Braun ThermoScan and insert gently into the ear.