As the name implies, miniature balls are smaller than 3mm diameter are considered miniature. Miniature balls are produced by totally different methods than commercial bearing balls.They are usually made of stainless steel or chrome and have good anti-rust and wear properties, making them durable in a variety of applications. Chrome alloy steel and type 440C hard stainless steel are the generally used materials in commercial balls.They are widely used where high precision is required, such as in the medical, automotive or electronics industries.