Garvey's Office Products Plastic Comb Binding,1/4",19 ring, Red, 100/Bx
19-ring plastic spines won't scratch, chip, peel or discolor. Bind 11 x 8 1/2 documents. Compatible with GBC and other plastic comb binding machines. To select correct diameter, measure thickness of material (including covers) and add 1/8". These spines are 1/4", 19 ring and packed 100 per box.