Plastic media is used for vibratory/disc/rotary etc polishing machine, suitable for soft parts such as zinc,alumimiun,brass,alloy etc.
The most common shape is cone shape, pyramid shape, triangle shape. 

Plastic Tumbling Media Application: 

* Deburring Brass and Aluminum Parts
* Plastic and Rubber Smoothing
* Machining Lines Removal
* Edge Rounding of Softer Parts
* Pre-Plating Finishing