In the grey thing I keep all the very handy loose items one might need, primarily of a medical nature.
Assorted dressings, plasters and hydrocolloid dressings (mine have expired and need replacing. Take the expiry dates seriously on any adhesive dressing as it is the adhesive component that degrades). I also have Imodium, paracetamol, ibuprofen, aspirin and some basic night and day flu capsules. Antiseptic cream and tape. Rubber gloves and a condom (as an emergency water carrier/makeshift waterproof container. If you want to go flavoured then have at it! Doubt it’ll flavour the water though.)
2x sets of Spare batteries for the head torch, spare lighter, cyalumes, Leatherman multi tool, Vaseline, Silva compass, matches, firesteel, one block of Hexy and two little waterproof containers (one filled with cotton wool, the other will have another accelerant - usually smokeless gunpowder)
One other thing lives in the top flap, that’s the toilet kit. Toilet roll and hand sanitizer.