RS PRO Black PVC 20mm Cable Grommet for Maximum of 16mm Cable Dia. / 605661

RS Pro Blind Grommets with Diaphragm. This range of RS Pro blind grommets (also known as closed grommets or hole-plugs) feature a diaphragm.. Options available:. ; 605-661 605-661 - 20mm ; 605-677 605-677 - 25.5mm. What is a diaphragm?. The diaphragm is a thinner PVC film that sits in the hole of the grommet. It surrounds smaller wires securely, for guidance and protection. A preformed hole enables easy cable entry/exit. The diaphragm sits snug around the wire to provide a dust tight seal which is essential in many electrical installations.. Where are diaphragm grommets used?. RS Pro PVC grommets are popular for use with metal back boxes. They fit into the pre-cut discs on most metal back boxes. Wires are then thread through the hole and supported by the surrounding diaphragm. The grommet ensures that the wire passes through the hole without coming into contact with the metal box. It also provides protection for the wire.. Features:. Black PVC Diaphragm with hole for wire Dust tight around wire Pre-formed hole