Realistically, the contents of your FAK should reflect the training and experience you have received in emergency care. What is in your head is more important than what is in your kit. Realize that many items can be readily and satisfactorily improvised (like splints). It is probably a good idea to have a variety of sterile materials and tape available in almost any FAK. I always keep a few band aids in my wallet where their ready availability takes care of the majority of day to day situations quickly and without fuss.