Varying with the design, line bushings can be used in intrinsically safe, measuring, control or energy circuits
By the plugability you need a locking ring and a screw up protection
Standardized the diameter is 10mm up to 40mm variation on this must be approved by a notified body in the case of Ex application.
The use of the 'two-path' - line bushing is recommended if the location of the strands must be variable to the final assembly, regardless of the final position of the screwed sleeve. Until the final assembly, the cable bushing is rotatable and shall fixed after completion (mandatory)
Here you will find a video (1:40 min) about the use and installation of a two-path line bushing.-->