4" grommet ring. Protect cables with these rubber grommets. The 30 ft. GR030 can be custom cut for any opening. GK4 grommets work with any 4" trade-size electrical knockout and resist cable chafing. The NEW GK-4G gland grommets additionally block dust and help control airflow within an enclosure. 4" grommets are sold in packs of four. Quantity: 4.