This product is made up of 2 components, a solid plastic surround to provide a firm base to screw through. The second component is a rubber like diaphragm, which can stretch from 5-11mm and provides a tight seal around any pipes or cables it surrounds...
As used by some manufacturers on shower valves when the cranked legs supplied are not long enough. The are 3/4" - 1/2" straight leg complete with new cover plates and back nuts...