Using your Sea to Summit sleeping bag liner is easy. Just unroll it and place it inside your sleeping bag. For the Mummy version, adjust the drawcord at the footbox for a cozy fit. If you're using the Rectangular model, put your Aeros Pillow in the sleeve. When you need to use the bathroom during the night, open the base drawcord of the Mummy liner and you can move around easily. Remember to keep your liner clean. You can machine - wash it on a gentle cycle with mild detergent. Avoid using bleach or fabric softeners as they may damage the fabric. After washing, let it air - dry. Store it in the provided storage case when not in use to keep it clean and protected. This will help ensure your liner lasts for a long time, thanks to the Sea to Summit Lifetime Guarantee.