Areas of use: the direct Cerustop filters fit many hearing aids from the brands WIDEX, PHONAK, RESOUND, AUDIO SERVICE, UNITRON, HANSATON and much more.Diameter: these white hearing aid filters have a diameter of 1.3 mmFilter change the CeruStop filters can be easily and easily changed thanks to the practical replacement tool (black interchangeable pin).Compatibility: same size as the Widex Cerustop, Phonak Cerustop and Widex NanoCare filters (1.3 mm diameter)Better language understanding we recommend replacing your filters regularly every 1-2 months. Usually a duller or quieter sound of the hearing aids indicates that a filter change is pending.Pack a grey box always contains 8 individual filters. Each filter is mounted on a black interchangeable pin