Eliminate sharp edges  

Automotive rubber grommets have virtually the same advantages as bushings.  It is the main function of rubber grommets and bushings.  The biggest danger to wires is damage when they pass through sharp-edged holes.  Rubber grommets fit holes of all sizes and insulate the wire from those sharp edges.  

Aesthetic temperament and interest  

This is an advantage of automotive black rubber grommets over bushings.  If rubber grommets will be installed on surfaces that will be seen by others, this is something you should consider.  Imagine the shiny tires on your car whether your car is an old bucket or straight off the production line, those shiny tires will give it some sparkle.  Rubber grommets are shiny tires for your wires.  

Different sizes  

Another huge benefit of rubber grommets is that they come in a variety of sizes more than 100.  You can choose from several different hole sizes and different panel thicknesses.  You can find rubber gaskets that fit holes, ranging in diameter from 6.4 mm to 60.3 mm.  In terms of panel thickness, rubber grommets can accommodate panel thickness from 1.6 mm to 4.8 mm.

Water resistance  

The rubber grommets is very waterproof.  In addition to being resistant to water, they are resistant to most modern chemicals and organic acids.  This is extra protection for your wires, tubing, and anything else you would pass through a rubber grommets.  

Vibration reduction  

Some types of bushings also have this property to protect the wire from vibration.  These sleeves have flexible "shutters" inside that allow wires to pass through, keeping them away from the outer edge of the casing.  On the other hand, the rubber grommets itself is thick and strong enough to shield the wire from vibration.