When you first check into any unit, whether its recruit training, marine combat training, military occupational specialty, or your specific unit after all of your training is completed. Even then, as a marine in the fleet marine force, you have chances to go to school which train you more in depth of your mos. When there, they issue you the basic things you need for that kind of training environment. Like motor vehicle operators course, you are given everything that was issued to you in boot camp. Flak Kevlar, sapi plates, main pack, cold weather gear, an assault pack, and many other things.
Some of the gear that is issued to you has a serial number on it. That number is specifically issued to you, so that way when you turn everything back in after you reenlist, got out of the military, pcs, or possibly change to a different mos, division supply can track exactly what was issued to you, and the date when it was actually issued to you directly.
Like I said before, you even have to keep track of your personal gear. For example, anything you wear, or something that you buy from the store, you either have to make sure that you keep track of who uses it, or who you lend it to. Cammies for example, you always have to make