Automatic & Assisted

Automatic and assisted-opening knives both get a blade out one handed, by different mechanisms. An automatic uses a spring released by a button and opens with no blade contact at all. An assisted knife requires you to start the blade with a thumb stud or flipper, after which a torsion bar completes the motion.

The distinction is legal as well as mechanical, and it varies considerably by state and sometimes by city — several jurisdictions treat automatics quite differently from assisted knives, and blade length limits sit on top of that. Check your own state and local rules before ordering, and take the same care when travelling.