Won''t scratch, chip, peel or discolor. 19-ring plastic spines 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". Binding Spine Type: Comb, Global Product Type: Binding Spines, Sheet Capacity: 25, Spine Diameter: 1/4 in.