Protech Stinger Automatic Knife. The Protech Stinger is a great little california legal automatic knife. The Protech Stinger is small but very capable. Made of the finest materials available the Protech Stinger automatic knife will stand up to whatever you can throw at it without frightening the neighbors. Specs: Overall Length: 5.25", Blade Length: 1.95", 154 cm, rc 59, handle: 6061 T6 aircraft aluminum.