Pre-Sized Coil Zippers, One-Way Separating. YKK brand.
36″ have a single tab slider. 120″ has a double tab slider.
One-Way Separating zippers are used on jackets, sleeping bags, hammocks, etc – Anywhere you need to be able to completely separate the two sides and reattach later (like the two sides of a jacket).
Factory sized, One-Way Separating zippers can be shortened by cutting the top end (opened end) to the length you want.