Plug with smoke pattern made of glass

The plug you can see in the picture is made of glass, and you should see it with your own eyes because the photograph doesn't do justice to the incredible 3D effect. 

The plug is made of transparent glass, except for the black background that is there to show the smoke. It's not really smoke, but a static pattern with a smoke-like effect. On the other hand, the effect is different from one model to another, and bigger in larger size plugs. 

Choose the plug in your gauge size between 2g and 5/8" (6 to 16 mm).