GBC A4 Binding Combs - 51mm - Black - 100 Pieces [4028187] Large capacity combs to bind up to 450 pagesEasy to bind and un-bind, ideal for Larger documents, can be cut to size for smaller documents, compatible with all 21 ring comb binding machines.Binding Capacity (Pages) - 450 SheetsBinding Type - CombBrand - GBCColour - BlackContents - 100 PiecesDimensions - 5.1 (W) cmFor Format - A4Manufacturer Part No. - 4028187Material - PlasticNumber of Rings - 21 RingsProduct Type - Binding CombsRing Diameter - 51.0 mmSize - A4Spine Width - 51 mmSuitable For - A4 Binding