Specialized airtight zippers are used in high-stakes gear such as scuba suits, hazmat suits, and even spacesuits, as worn by Neil Armstrong. These zippers are much stiffer than standard ones because they must maintain a complete seal. If you were referring to the " Joe Zip" merino sweater
However, if you are looking for an regarding zippers generally, here is a fascinating fact:
, its key features include being made from 100% extra fine Merino wool and providing a comfortable, breathable fit that prevents overheating. Joe Zip Interesting
Based on your query, it seems there might be a mix-up between a file name ("FN0006.zip") and a specific product or fact, as the search results primarily point toward a "Joe Zip" merino wool garment or " High Level Bridge fn0006 " photo products.