1st line - Worn on your person at all times. Includes in pants pockets, drop holsters from pants belt, etc.
E & E - Contained on your web gear/LBV and pistol belt (usually includes a butt pack). If one has to move quickly, they can drop their rucksack and survive off their web gear/butt pack.
Ruck - Inside your rucksack/pack
Sustainment - Extra comfort items in duffle bags, rubbermaid containers, etc. These are kept at camp or in a vehicle.
1st line gear
Survival kit (mini, altoids type) [shown below]
Combat knife (in drop holster w/ sharpening stone)
Sidearm (in drop holster w/ 1 extra mag)
Multi-tool (Leatherman, Gerber, etc.)
Locking folder (small blade, 3 1/2 in or so)
Firestarting (matches, lighter)
Energy bars/snacks
550 cord (25')
