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 ,loose leaf rings size has: 14mm 19mm 25mm 32mm 38mm 50mm 63mm 75mm.blister card package is more easy take and looks more clearly.