Tungsten carbide ball is a unique category of balls because it is manufactured in a sintering process, whereupon the metal powder is formed under extreme heat and pressure. Tungsten carbide ball is extremely hard. The manufacturing technique makes tungsten carbide ball substantially more expensive than other materials, but practically inert. Their relative inertness makes them extremely resistant to interaction with various liquids and alloys. Tungsten carbide balls can be found in heavy machinery applications, since they are much stronger than stainless steel or chrome. Particularly, tungsten carbide ball has been used in industrial sprayers to regulate the flow of fertilizers or pesticides to crops.