Binding Supply
Mead CombBind Binding Spines - 0.43" Maximum Capacity - 70 x Sheet Capacity - For Letter 8 1/2" x 11" Sheet - Plastic - 125 / Box
Amazon
Mead CombBind Binding Spines/Spirals/Coils/Combs, 7/16", 70 Sheet Capacity, Black, 125 Pack (4000133)