What makes a lock genuinely high-security
The term high-security is used loosely in hardware marketing. In the locksmith trade, it has a specific meaning: cylinders rated under UL 437 or equivalent standards that demonstrate pick resistance, drill resistance, and key control in objective testing. Pick resistance means a trained lockpicker with professional tools cannot open the cylinder in under five minutes. Drill resistance means hardened steel and anti-drill pins prevent core extraction. Key control means the keyway is patented and keys cannot be duplicated without authorization.
The three brands most consistently cited by security professionals and specified by architects on institutional projects are Medeco, Mul-T-Lock, and ASSA ABLOY High Security (marketed as Abloy in North America for the most demanding applications). Each uses a fundamentally different mechanism to achieve resistance. Understanding the mechanism explains the real-world tradeoffs.
Medeco: rotating and elevating pins
Medeco cylinders use a dual-action pin system: each pin must both rise to the correct height (standard to all pin tumbler cylinders) and rotate to a specific angle before the cylinder can turn. This secondary rotation requirement defeats standard picking because pick tools that address height do not simultaneously control angle. Medeco also uses a sidebar mechanism that must engage correctly across all pins before the cylinder opens.
Medeco M3, the current flagship line, adds a third-generation key control system with a registered keyway. Keys are only cut at authorized Medeco dealers with owner identification on file. The keyway itself is patented, making duplication at retail impossible. Medeco cylinders carry UL 437 listing and meet ANSI Grade 1 standards. They are the dominant specification in US government buildings, embassies, and institutions with strict key accountability requirements.
Limitation: Medeco's pin system, while excellent against picking, is susceptible to high-sophistication impressioning attacks by skilled locksmiths. This is a theoretical attack in most residential and commercial contexts but a real consideration for the highest-security installations. Medeco M3 introduced changes that significantly increased impressioning difficulty, but Abloy disc detainer cylinders remain more resistant to this specific attack vector.
Mul-T-Lock: telescoping pins and anti-pick springs
Mul-T-Lock's primary innovation is the telescoping pin: each pin has a secondary pin inside it, creating a pin-within-a-pin configuration that must align at two depths simultaneously. This doubles the number of shear points an attacker must simultaneously address during picking. Combined with anti-pick springs that resist manipulation, Mul-T-Lock cylinders achieve exceptional pick resistance through mechanical geometry rather than the angular mechanism Medeco uses.
The MT5+ and Classic series both carry UL 437 ratings. Mul-T-Lock's key control system uses a patented telescoping key profile that requires both a registration card and factory authorization for duplication. Unlike Medeco's dealer network, Mul-T-Lock key duplication goes through the factory for the highest-security variants, creating a paper trail for every key issued.
Mul-T-Lock is particularly strong in commercial and multi-tenant applications because the master key system math — the mathematical combinations available for large key hierarchies — scales better than some competing systems. A property with 200 units, common area locks, and management master keys requires careful key system design; Mul-T-Lock's system supports deep hierarchy without exhausting the key combination space.
ASSA ABLOY High Security: disc detainer mechanism
ASSA ABLOY's highest-security cylinder line, marketed as Abloy Protec2 in North America, uses a disc detainer mechanism fundamentally different from pin tumbler designs. Rotating discs instead of pins must align through key-driven rotation; there are no springs in the mechanism. The absence of springs eliminates the vulnerability that picking exploits — there is nothing to set. The cylinder is effectively immune to standard pick and bump attacks.
Abloy Protec2 also incorporates a rotating disc that is unique to the key's profile, making impressioning extremely difficult. It carries UL 437 listing and is the specified solution for the most demanding institutional, military, and critical infrastructure applications globally. The tradeoff is cost: Abloy cylinders are the most expensive of the three, and qualified installation technicians are fewer in number.
ASSA ABLOY as a parent company also owns Medeco, Yale, Sargent, and other hardware brands. When a specification calls for ASSA ABLOY products, the specifier should clarify whether they mean the Abloy disc detainer line or one of the other brands in the portfolio, as security levels vary considerably across the family.
Side-by-side: choosing the right brand for your application
- Residential high-security upgrade: Medeco M3 or Mul-T-Lock Classic are the most common specifications, with established dealer networks in the DMV area
- Commercial master key systems: Mul-T-Lock MT5+ for large systems with deep key hierarchies; Medeco M3 for government-standard key accountability
- Maximum pick and manipulation resistance: Abloy Protec2 disc detainer, particularly for installations near sensitive areas or embassies
- Budget-conscious high-security: Mul-T-Lock Classic offers UL 437 protection at a lower price point than M3 or Protec2
Related services
- High-security lock installation: /services/high-security-locks
- Master key system design: /services/master-key-systems
- Commercial locksmith services: /services/commercial-locksmith
Frequently asked questions
Are high-security locks worth the cost for a home?
For most residential applications, a Grade 1 deadbolt with reinforced strike plate addresses the real risk (kick-in forced entry) better than high-security cylinders at far lower cost. High-security cylinders are most justified when the threat includes covert entry — picking, bumping, or key copying — which applies to home offices with sensitive documents, executives with high-profile roles, or rental properties where key accountability is critical.
Can a locksmith install any of these brands?
Installation is standard locksmith work for all three brands. The key control and registration system requires the locksmith to be an authorized dealer for the brand — ask for dealer credentials before purchasing a high-security cylinder. An unauthorized dealer cannot provide the key registration documentation that makes these systems valuable.