The fabric chosen to make the original Parkas was key to the design and performance of the product. Ballistic nylon, a high tenacity nylon 66, was treated with a fluorocarbon coating and neoprene lamination on the inside of the fabric. The finished material is scuff proof and slash resistant, waterproof and fireproof. Ballistic nylon was developed and supplied by the Ministry of Defence. It was originally intended for use as blast-proof curtains in bomb disposal as well as in protective military flak jackets.