PVC 4:1 Pitch Spiral Binding Coil 8mm, Black, Pack of 100 12-inch long Spiral Coil Binding Spines (Pack of 100) 4:1 Pitch, 4 loops per inch 8mm (5/16" inside diameter) Binds up to 52 pages of standard 20 lb bond paper Colors May Vary Somewhat from Photos, Manufacturer's Color designation is Black (PMS 433 C)