Rust is a survival game, where you can constantly encounter both enemy NPCs and regular players who are eager to kill you and take all your loot. Constant raids can chase you anywhere and deliver a lot of unpleasantness, so you should never forget about the means of defense. One of them is a first aid kit, which is indispensable in the conditions of Rast, and can repeatedly save your life. I suggest a little more detailed breakdown of ways to find it, and how it can be used.
A large first aid kit requires a lot of your resources, but it is definitely worth it. It can only be made on a level 2 or 3 workbench. For this you will need 2 syringes and 10 units of low quality fuel.
The first aid kit can not be studied on the research table, and therefore it will have to be found in the open world. They are found in many crates with medicines, and have a good chance of falling out, sometimes up to 50%.
To use it quickly, you need to put it on the most convenient quick slot. This way you can efficiently swap between the slots you need, and use what you need in a short time. Also keep in mind that a first aid kit placed in a quick slot can easily lift you from a knocked out state, as well as quickly restore your health to 100% and stop bleeding.
The first aid kit is one of the most important items in the game, and therefore can craft in large quantities to save you on the battlefield. To do this, you can use a bind that will free up your time considerably. By pressing the "F1" button, you will open a window with an input line. There you need to enter the command "bind craft.add -2072273936". Instead of "button" set the key that is convenient for you for this function.