Description Pack of 3 charcoal filters for waist mounted regulator that comes with the FMT3005 Air Fed Mask. Only genuine parts should be used to ensure safety standards are maintained and product compliance is not invalidated. Suggested replacement frequency is every 3 months. If there is a noticeable restriction in airflow or odours can be smelt when wearing the head top, then the filter should be replaced immediately. Failure to replace with genuine parts will invalidate product compliance.