black, 1.high, strength, reinforced Bakelite, resistant to solvents, oils greases and other chemical agents, 2.making this knob for using on medical machines, equipment for the food and pharmaceutical industry 

3. wherever hygienic, climatic and environmental factors or laws make it mandatory to use corrosion resistant magerials.

4.we can  provide you with the best quality, after-sales service and the lowest price.if you want special size we can make them according to you requirements.

5.They are used for the modern and the traditional machinery extensively, and bring some advantages for operating.