This listing includes a felt insulated cover with canteen and special cap for US military hydration systems such as the US M17, M40, and M45 gas masks with a Type M connector for canteens and bladders..  One quart potable water capacity.  Canteen color is olive drab made of sturdy plastic, does not collapse.  The cover has a belt hook hanger to attach to a gear belt and comes in various styles.  If you have a preference on the colr you can request the one you like, but we have no promise that all would be in stock.  These items may have been previously issued and may show signs of use, but are in excellent condition.  The connector cap will not work with the Israeli, French, or Soviet masks on this website, nor will it work with any mask with a built-in hydration system.  Will not work with a US M50.  The special cap does not alter the normal functioning as a canteen, you can still use it as you would any canteen.  See other listings for more photos of the canteen and cap and the applications with a gas mask hydration system.