These are #10 Molded Tooth Zippers. They are strong, supple zippers.
These are specifically engineered for marine applications but can be used for wind screens, tents, sleeping bags. The teeth are RESIN not PLASTIC.
Zippers are really interesting! Strength & longevity are dependent on the material used in the injection process to produce the teeth, as well as the size of the teeth. So if you have a #10 zipper that is made out of PLASTIC, it is best used inside in a low-strength product. Price is relevant to the materials used. A PLASTIC zipper is much cheaper (or should be) than a zipper engineered to last outside (UV protected) in an environment including salt and sand.
And in ALL environments, when a zipper fails, it is a combination of the zipper being under-engineered for the end use & operator error. If you are in a salt environment, your zippers will last longer if you wash the salt off them before the salt dries.
If properly taken care of, my zippers are warranted for 7 years!
ps- PLASTIC is a generic term that can be any combination of materials that are extruded into the zipper tooth mold. Just like "metal".....