1/4" calendar binding/6.4mm calendar binding rings
Double ring binding
size Pitch(mm) inches mm inches mm pages(80g) 1/4 6.4 3:1 3/16 4.8 45 5/16 7.9 3:1 1/4 6.4 60 3/8 9.5 3:1 5/16 7.9 75 7/16 11 3:1 3/8 9.5 85 9/16 14.3 3:1 1/2 12.7 120 1/2 12.7 3:1 7/16 11.1 100 5/8 16 3:1 9/16 14.3 135 5/8 16 2:1 9/16 14.3 135 3/4 19 2:1 5/8 17.5 165 7/8 22.2 2:1 3/4 20.6 180 1 25.4 2:1 7/8 23.8 200 1-1/4 31.8 2:1 1 25.8 220