The filter is a special resin-impregnated sheep's wool element which combines the important property of having a minimal resistance to airflow with the necessary electrostatic and hydrophobic characteristics to trap the extremely small particles of Technegas. Under no circumstances should this filter be cleaned in any way for reuse, as its vital absorption properties WILL be compromised.

Ordinary paper filters, if sufficiently thick to trap all the particles, will offer too much resistance for safe administration to patients and will almost inevitably cause patients to defeat the mouth seal and exhale Technegas into the camera room. Users are advised to adhere strictly to the technique evolved over many years of experience to be the best administration procedure for both patient and staff.