Compatible with any standard 19-ring comb-binding system These black plastic comb binding spines have a 1/4-inch diameter and provide a custom look for your official documents. These spines can hold a 20-sheet document with a 19-ring comb binding system. 20-sheet capacty. 25 combs per pack. Use with any standard 19-ring comb-binding system. Gives a professional appearance to bound documents. Durable plastic. Binding combs. 25/pack. Sold as 25/Pack.