Some of them are lined with ripstop nylon. The fun part of this nylon? This is nylon that has been to SPACE. Yes, you read that right. My grandfather is one of the founders of the Poker Flats Research Range. My grandfather proposed a rocket range in the 1960s that would shoot rockets into the aurora and deliver payloads of various chemicals to the high-altitude regions. You can read about it here. He has a shirt that says, "I AM a rocket scientist." He's a funny dude. Several years ago, they dedicated a building to him and gave him the parachute of the most recent rocket launch. Being The Fabric Queen, I ended up with some of it. My dad will be getting the baggies that are made with the parachuting material. He'll think it very fitting.