These plastic bags are a lightweight, transparent variation on fabric drawstring bags. With the same pull-to-close opening, they're great for holding product parts or bundling smaller products. While they don't have the steadfast closure of a zip top bag, they have a bit more finesse. They can be reused, especially when made with thicker films for more durability.
Drawstrings are usually made from plastic-based materials — either nylon or HDPE.