High Security Locks

High Security Locks: ASSA, Medeco, Marks, Mul-t-lock

Not looking for high-security but want the best standard locks you can buy? Check out our favorite door locks article.

High Security Locks : Best Locks to Stop Theft & Key Duplication

Call for High Security Lock Products


  • High security locks are extremely pick resistant – requiring special skills or tools not widely available
  • Are Bump Proof
  • Are made of the Strongest Materials
  • High security locks have keyways that can’t be duplicated by employees, workers, or home Service Providers. When you get the key back, you know they haven’t made copies.
  • No Unauthorized Keys Made from a Photo sent online
  • Compare the three main high-security brands: Medeco, ASSA and Mul-t-lock

ACME Locksmith sells, services, and repairs high security locks by Medeco, ASSA, Marks, and Mul-t-lock High security locks.  

Though primarily for commercial services, we see an increased number of customer asking for high security products in our residential services.

These locks protect your home or business by ensuring that no unauthorized key copies can be made and high security locks have the highest lock grading because they are built with the best materials. High security locks provide the maximum security possible. The following information is from Mul-t-lock (our preferred high security lock brand) but applicable to all other brands.

Medeco High Security Assa Lock

Get The Strongest Lock

High security locks are made of the strongest material. Locks are heavier, screws are thicker, and they often contain other anti-theft measures. They are also bump proof locks. That is, there exist no key that can be used to bump the lock.

High security locks often weigh 2X that of a standard lock. Additionally, locks like Mul-t-lock product have included technology that can secure the bolt of the lock to the frame so that they cannot be seperated.

Establish Key Control

Businesses relying on keys that are stamped as Do Not Duplicate (DND) currently have NO protection from an employee or member making as many copies of that key as they wish.

High security locks, such as the MUL-T-LOCK, are patented keyways. They are issued to specific locksmith or security companies. This means that only the company that provided you the high security key can make a copy of it. No one else in the region has access to that key blank. High security keys are the best way to establish key control.

As an example, ACME Locksmith owns a specific Mul-T-Lock keyway. We are the only locksmith in the Phoenix region with this specific keyway and are the only locksmith that can make you a key. When keys are not patent protected any company can manufacture the key, any company can buy it, and any company will copy it.

There are varying levels of restricted keyway protection to gain key control. Which is right for you should be discussed with your commercial locksmith service.

  • No protection. Widely available keys that can be copied in any machine at any big box store.
  • Restricted keys. Keys that are only sold to security companies, such as locksmiths. They aren’t generally available at big box stores. The benefit of these keys is that the locks they go to are generally high security so offer all of the protections of a high security lock, and you can get duplicate keys more easily (by presenting a verification card issued when you bought the high security locks), because you can go to any locksmith.
  • Patented keys. The strongest key control. Your keys can only be made by one company in your region and will only be made when someone presents the verification card.

Brands Our Commercial Locksmiths Carry for High Security Locks

Marks: Restricted Keyways – Prevent Duplication – Affordable High Security

  • A budget oriented lock with a restricted keyway
  • Can be installed in most existing hardware by simply replacing the cylinders
  • Stops unauthorized key duplication (card must be presented)
  • Ideal for businesses that hand keys to employees
  • Ideal for rental homes and condos – get the keys back, no need to rekey
  • Side bar locking system to prevent picking and bumping

Mul-t-Lock: Highest Security Locks and Keys

Mul-t-lock Deadbolt
Mul-t-lock’s Bolt and Strike Join Together
  • This is our favorite high-security lock
  • The strongest security and materials
  • Bump and drill resistant
  • Has three levels of security built into the key
  • Keys can only be duplicated when a key card is presented, ensuring no unauthorized duplication. When you get the key back, you know no one made a copy
  • Can get a restricted key option or a patented key option for more control
  • Contains a retaining bearing preventing the lock from separating from the door frame. No other high security lock offers this feature. It’s unique to Mul-t-lock and why we use it. Check it out on Amazon
  • Lifetime finish warranty with limited lifetime mechanical warranty.
  • In addition to high security door locks, Mul-t-lock, Assa, and Medeco also provide high security pad locks and high security gate locks.