Automatic knives or switchblades are restricted knives that open by pushing a button or pulling a lever. These styles of knives are often used by Law Enforcement, Military, Emergency Medical personnel, and other individuals who need a knife that can be opened with only one hand.
Once activated, Automatic knives quickly push the blade out into its deployed position. Despite them being very useful, they are legally prohibited or heavily restricted depending on your location. Check your local laws before purchasing.