LWM

A First Aid Kit is one of those tools that should ALWAYS be in your 4X and for that matter any other vehicle you drive as well. When I was the scoutmaster of a local Boy Scout Troop I had the honor of following in the footsteps of an Emergency Room Doctor who was not only a great Scout Master but a Great man. He really held to the motto of "Be Prepared" and the troop first aid kit was no exception.

There are many sources for information on first aid kits but I think one of the best out there is the American Red Cross. The Red Cross posted the following information on their web site:

Anatomy of a First Aid Kit

A well-stocked first aid kit is a handy thing to have. To be prepared for emergencies, keep a first aid kit in your home and in your car. Carry a first aid kit with you or know where you can find one. Find out the location of first aid kits where you work. First aid kits come in many shapes and sizes. You can purchase one from the Red Cross Store or your local American Red Cross chapter. Your local drug store may sell them.

You may also make your own. Some kits are designed for specific activities, such as hiking, camping or boating. Whether you buy a first aid kit or put one together, make sure it has all the items you may need. Include any personal items such as medications and emergency phone numbers or other items your health-care provider may suggest. Check the kit regularly. Make sure the flashlight batteries work. Check expiration dates and replace any used or out-of-date contents. The Red Cross recommends that all first aid kits for a family of four include the following:

2 absorbent compress dressings (5 x 9 inches)
25 adhesive bandages (assorted sizes)
1 adhesive cloth tape (10 yards x 1 inch)
5 antibiotic ointment packets (approximately 1 gram)
5 antiseptic wipe packets
2 packets of aspirin (81 mg each)
1 blanket (space blanket)
1 breathing barrier (with one-way valve)
1 instant cold compress
2 pair of nonlatex gloves (size: large)
2 hydrocortisone ointment packets (approximately 1 gram each)
Scissors
1 roller bandage (3 inches wide)
1 roller bandage (4 inches wide)
5 sterile gauze pads (3 x 3 inches)
5 sterile gauze pads (4 x 4 inches)
Oral thermometer (non-mercury/nonglass)
2 triangular bandages
Tweezers
First aid instruction booklet

Another source for building your own first aid kit is Wikiedia, there you will not only find a list of the most needed items but a short description of what those items are used for.

So before you hit the trail do yourself and those traveling with you a favor and make sure you have a first aid kit on board.