The Bloc shape is Granite Gear"s innovation to help you pack more efficiently inside your pack. Compared to a round shape, the bloc fits better into the corners of your pack, they stack nicely, and eliminate all the "dead air" that can happen when you try to pack with round stuffsacks. Less dead air means better load stability, quicker pack loading, and the possibility of carrying the same amount of gear in a smaller pack, saving you weight. Features: - Compress your lofty items to a rock hard state without bulging. - Bloc shape stacks and nests together. - Designed for years of use and abuse. Accept no substitutes! - 210D Nylon