Communicate your ideas with professional polish. 19-ring plastic spines won t scratch chip peel or discolor. Bind 11 x 8 1/2 documents. Editing capability with a machine. Compatible with GBC and other plastic comb binding machines. To select correct diameter measure thickness of material including covers and add 1/8 . Sheet Capacity: 90 Spine Diameter: 0.5 Number of Rings: 19 Colors: Black.