Product properties: These steel balls are made of AISI52100 chrome steel,assortment of 1", 7/8", 3/4" and 5/8" to meet your basic requirements for coin rings. Product advantages: These balls are highly polished, with high precision and excellent surface finish. Warm note: 1)These small size balls are solid steel, please keep them away from children under 5 years old to avoid choking. 2)Although these chromium steel balls have good rust resistance, but it is recommended to use a dry cloth to wipe clean after use and apply a layer of oil, so that they have better rust resistance, to extend their service life.