Here are pictures of the large brass #10 YKK zippers that I use on some of my custom and handmade leather goods. These are hand sewn in using bees waxed nylon thread. The holes for it are pre-punched and spaced 1/4" apart. All of these pictures are clickable for larger views.
These are #10 YKK brass zippers. Years ago I used smaller zippers, but, they were the first thing to wear out. Customers didn't like that and I didn't like having to replace them. Subsequently, I switched to these larger ones and I have heard appreciation about that switch. If anybody did want smaller zippers I could certainly do those as well.