What is an Assisted Opening Knife?

Assisted Opening knives or Spring Assist Knives are a type of knife which uses an internal mechanism to open the blade from a closed position when slight pressure is applied to a thumb-stud or similar type device.

Well what does that mean? 

It means a super fast opening blade using just one hand and Spring Assist Knives are 100% legal to own in all 50 states but your local laws might restrict them from being carried into public or might have concealment or non-concealment laws. You can read the law at Assisted Opening Knives Law. This statement is based on Federal Law but remember that local, county & city laws can be harsher than the Federal Law and that State Statues & Local Laws take precedence. Please check with the local officials where you live and ask them about the knife laws that are applicable to you.

There are differences between a Switchblade and Assisted Opening Knives.

SWITCHBLADE

A switchblade (also known as automatic knife, switch, or, in British English flick knife) is a type of knife with a folding blade that springs out of the grip when a button or lever on the grip is pressed. There are two basic types: side-opening and out-the-front (OTF). A side-opening knife's blade pivots out of the side of the handle (in the same manner as an ordinary folding knife). An out-the-front knife's blade slides directly forward, out of the tip of the handle. Many OTF (out-the-front) knives work with a dual-action mechanism that enables the user to extend and retract the knife in one press of the finger, with no cocking or priming action. However, some OTF (out-the-front) knives are single action, and require the user to manually retract the blade. A wide variety of blade designs may be found on switchblades, but the most common is the Italian stiletto style seen often in movies. However, the switchblade should not be confused with the butterfly knife (balisong), assisted-opening knife, or the non-automatic stiletto.

Assisted-Opening Knife / Spring-Assisted Opening Technology

A spring-assisted knife is a knife that when you push on the thumb stud to open it a spring takes over and propels the blade open. Spring-assisted knives make a great alternative to automatic knives. A Spring / Torsion assisted knife is a type of knife which uses a spring assisted mechanism behind the blade. They open by the ambidextrous thumb stud on the blade with a slight bit of pressure. They are commonly confused with switchblades, but have one main difference. While a switchblade can be opened usually with the push of a button within the handle, the user of a spring-assisted knife must apply slight pressure to the thumb stud and the spring/torsion assisted mechanism does the rest. Once the knife has been opened about one-quarter of the way (45°), the mechanism will open the knife the rest of the way. A/O knives are Assisted - Opening which are also Spring - Assisted knives.