Aluminum Metal 1/4 inch 3-6mm ID STRAIN RELIEF DOME NUT IP68 PG7 Connector fits a 1/2 Inch Hole.

.28" ID .49" OD Resistant to most chemicals and solvents.IP68 Easy installation: push cable through strain relief and tighten dome nut. Black anodized aluminum. Use minimum size strain relief that fits your cable. Ideal for control cabinets, car washes, hot tubs, instrumentation