Open domes are recommended for those with mild to moderate hearing loss. They provide a more natural sound but can cause feedback in high-volume settings. To ensure your hearing aids optimal performance, we recommended changing ear domes every 3 months or whenever: Ear domes are damaged Ear domes become stiff or discolored Ear domes do not fit well You experience an increase in whistling Available in 3 sizes, small (6mm), medium (10mm), and large (12mm.) Top-quality domes for sensitive skin.This accessory fits the following devices: Otofonix Elite Hearing Aid Otofonix Encore Hearing Aid Otofonix Apex Hearing Aid Otofonix Helix Hearing Aid