Home / Unitron / SDS 4.00 Open Dome Med SDS 4.00 Open Dome Med£10.00 Phonak advise that domes should be changed every three months or when it becomes stiff or brittle. This is to prevent the dome from detaching from the receiver sound outlet during insertion into or removal from the ear. SDS 4.00 Open Dome Med quantity — OR — Add to basket Categories: Unitron Domes, Unitron Product ID: 1692