Heavy Duty Large Binding Ring Hinged/Book Binder Ring, 4.1 Inch Diameter x3 In A Pack Multi-layered nickel-plating won't crack or split Locking position for extra security Easy to operate--pull to open and squeeze to close. Tough steel rings can handle heavy use Ideal for heavy fabric sample for the show room, A3/A2/A1 plastic sleeved portfolios, photographers, artist and designers.