First Aid Kits vary greatly in their style and supplies. I have seen anything from a small waterlogged bandaid box to a kit that would rival an Advanced Life Support Ambulance.
This said, My kit is fairly robust. It is an orange soft sided bag. It stays in the cabin of my boat, but most of the contents have been vacuume sealed to keep everything clean and dry.
This is from memory, so it may not be complete, but it contains:
BSI:
Gloves, gown, goggles, mask, N-95 resp., CPR Microshield, sm red bag
Diagnostic:
Cuff, Scope, Penlight, shears, paper, pen, Patient Care Reports, plastic survey tape (red, yellow, green, and black)
Airway:
O2, Oral airways (ad/ped sizes), Nasal airways (ad/ped sizes), Bulb suction, Tongue Blades, L'scope and ET Tubes (2 each 3.0-9.0), Magill Forcepts, tube restrints, end tidal CO2 detector, tube check (bulb style)
BVMs (ad/ped) with assorted masks
Trauma:
Bandaids, 2x2s, 4x4s, 5x9s, Trauma Dressings, Burn Sheet, 2" Kling, 4" Kling, SAM Splint, hot packs, cold packs, triangle bandages, two adjustable C-Collars
Medical:
Oral Glucose paste
Other:
OB Kit (has useful items like sterile drapes, scalpel, clamps, sponges, cover gown, chux pads, plastic bag and twist tie). This is a handy kit to have for many different medical/surgical type events, not just birthin' babies.
I also have some allergy issues, so I usually have epi-pens around.
I'm sure there is more, but that's what I could remember off the top of my head.
It should probably be stated that you should not carry anything that is outside of you level of training, or that you are not authorized to carry.
Stephen