[sdiy] name this piece...

[BrightBoy]

>"Strain relief"
>The ones made by Heyco being the most common.

Common, yes, but I think they put more stress/kink on the 
cable because of their design and are not as rugged.

A proper cord grip puts even pressure 360 degrees around the
cable and the connector body itself is bolted to the chassis.

Cord grips are the defacto standard in industrial machinery
for wiring sensors to junction boxes, etc.

(I spent 7 years as a controls engineer in a General Motors
manufacturing facility early in my career)

Jeff