Eagle Creek's Compression Sacs are nylon reinforced plasticised bags with 'non-return' valves at one end so you can expel the air from the bag.
Eagle Creek says:
Eagle Creek's Pack-It Compression Sacs have non-return valves at one end so you can put clothing into the bag, seal it, roll it and expel all the air from the contents, they then only take up a fraction of the space in your luggage. Very easy to use time and time again.
- Reviewed by Ultralight Outdoor Gear
Material: Polyethelene (nylon reinforced)