Tasers are not legal in all states so check your state regulations before contemplating a purchase.
The two main types of tasers are prong-type and dart-type:
The prong-type have either arcing (you can see and hear the electric charge going from one post to the other or non-arcing (can't see or hear electrical charge). The arcing taser will stop many animals and human in their tracks just by the sound/sight of the electical charge. The downside of the arcing taser is that it has to come in direct contact with the assailant, human or animal, for 3 - 5- seconds it.
The dart-type taser shoots out two darts which are contected to the taser by thin wires. Most have laser aiming built in the taser so you can see where the darts wil penetrate. Darts will penetrate clothing up to an inch in depth since they are fired by compressed air. Depending upon the model purchased, darts will travel 15 to 23 feet out from you. The advantage is the chance to incapacitate an assailant before reaching you.
Most tasers are reuseable. The dart-type tasers require purchasing a new dart cartridge after every use. Some companies will replace a cartridge at no cost if it was used in a documented self-defense situation.
Knives are another tool in hunting and self-defense. They come in varying sizes, blade configurations, fixed blade or folding blade. Knives are useful in many situations including hunting and survival kits.
Pepper spray is used to incapacitate an attacker, human or animal, by irritating the eyes and lungs. The spray comes in many sizes and strengths. There are spray units small enough for a key chain and large enough to spray out to 30 feet.
Effectiveness varies by species, wind conditions, and mental status of assailant. Pepper spray has been shown to be as effective as a firearm in preventing bear attacks. The bear's nose is so sensitive, that by using a high-strength spray with the 30-foot fog, bears retreated more often than with gunfire.