High Security Cylinders and Protected Key Stock

Lock manufacturers are depended upon to control the issuance of key stock.

In order to maintain key control, companies and institutions implement key systems and depend on lock manufacturers to control the issuance of key stock.

Lock manufacturers integrate new features into cylinders that are dependent on changes in the design of the key. When the key design is original, a patent is issued to protect the design, and the lock manufacturer is given exclusive rights to produce and furnish the key stock. This is the only effective means in which the lock manufacturers can control the issuance of key stock.

A patent is good for 17 years. When the patents expire, third parties are free to imitate the key stock and offer it without restrictions.

It usually takes several years for a key system to become popular. This shortens the protective interval in which the key stock can be protected.

To maximize the length in time in which key stock is protected, the lock manufacturers may wait to the last minute to introduce a new patentable design.

This article examines both past-and-future design changes that achieve patent-protective key stock while enhancing security.

Many companies offer patent-protective key stock. This article focuses on some of those companies that offer cylinders that can universally retrofit the different types of locking cylinders that companies and institutions already use. Consult your local locksmith wholesaler for their recommendations regarding high security lock manufacturers.

The companies that furnish the following key systems deliberately control the issuance of key stock so that end-users are assured that the ability to procure unauthorized keys is minimized.

All the lock manufacturers mentioned in this article concentrate on maintaining a supply of patent-protected key stock in as many common cylinder formats as possible. Just about every mechanical lock manufacturer is also developing electronic components if not complete systems.

As soon as a new patent is awarded to a lock manufacturer, that manufacturer continues the ongoing effort of developing the “next-generation” patent.

Locksmiths should be aware that any mechanical system they employ today should probably be changed out as patents expire.

It could be argued that the answer to continual replacement is to additionally support mechanical key systems with electronics.

Certainly there can be some electronic support for controlling access. However the cost of electronics, at least today, is more expensive than mechanical locks. A secondary factory is that electronics is still in an evolutionary stage as new products are constantly being developed and introduced.


These keys feature two sets of bittings.

The primary bitting set typically raises a standard set of six pins. Pin stacks may feature spool drivers.

The secondary bitting set is milled onto the side of the key and raises five special pins. Each pin features multiple “false” grooves, and one “true” groove. When all true grooves are aligned, the side bar is neutralized.

Usually the secondary bittings are static to guarantee exclusivity for a certain customer. When the customer orders key stock, the secondary bittings are pre-cut.

Hardened inserts are pressed into the face of the plug to resist drilling. One pin stack may be loaded with hardened top drivers to additionally resist drilling.

The Twin V-10 system was introduced as an upgrade to the ASSA Twin 6000 program. It included a coded sidebar, new profiles and patented key stock. It utilizes a standard cylinder plug profile (broaching). Various sidebar codes are used to create different keyways.

The UL437 version is called a “Twin Maximum.”

For more information, contact your local locksmith distributor or Assa Lock, phone 800-235-7482 or web site www.assalock.com.


The original design is based on rotating discs.

The shells of these cylinders are slotted for a round sidebar. Bittings are cut at the same depth but different angles on a round key. There can be up to 11 cuts corresponding to 11 discs. The discs are rotated with the movement of the key. At 90 degrees, if all the slots in the discs are aligned, the sidebar will retract.

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