Loose leaf rings ,sometimes is called book binding rings,card rings ,hinged snap rings ,it depends on different industry. it  is made of all metal and nickel finish , circle type makes you save more energy when you take large bags,making the lever files more tidy.blister card package avoides rusty,more durable using ,pvc tube mamde you use more convenient and take it easy.loose leaf rings size has: 14mm 19mm 25mm 32mm 38mm 50mm 63mm 75mm.