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

This range of RS Pro blind grommets (also known as closed grommets or hole-plugs) feature a diaphragm.

605-661 - 20mm
605-677 - 25.5mm

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.

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.

Black PVC
Diaphragm with hole for wire
Dust tight around wire
Pre-formed hole