What I want to share here concerns the length of the comb.  The aforementioned 11" long comb is designed to bind a standard 11" long by 8.5" wide (letter size - US) document at the left hand margin.  This allows the pages to be turned from right to left as is customary with 3 ring binders and preprinted books and magazines.  An 11" comb will have 19 "teeth" or "loops" that correspond to the 19 slotted holes punched in your document.