If you spend much time at all outdoors, sometime the need to make a note in the rain will occur. Then you will need some waterproof paper such as http://www.riteintherain.com/ (since 1916!) or http://www.myaquanotes.com/ etc. For example, Rite in the Rain’s smallest spiral notepad http://www.riteintherain.com/pocket-top-spiral-universal-3-x-5 weighs .12lb (55 grams). I usually just carry a couple of leaves from the notebook just in case I need to leave someone a message ( a will perhaps!) You will also need a light pen such as a waterproof pen refill http://www.riteintherain.com/blue-ink-refill-all-weather-pen or a Fisher’s Space Pen refill (http://www.spacepen.com/) @ 1 gram for the ‘U’ refill when you break the end off. It will even write under water or in space!