I’ve been in this business for a long time. And I can tell you, nothing stops an international project dead in its tracks like a hardware sourcing nightmare.

You get a spec sheet from a European architect. It calls for a "60/72" lock body or a "92 PZ" requirement. You take this to your usual US hardware supplier, and they just give you a blank stare. They have no idea what you're talking about.

This is a fast track to ordering thousands of dollars of incompatible scrap metal.

This is not a system you can "eyeball," "get close," or "make work." Getting it wrong means costly rework, project delays, and a very unhappy client.

So, let's settle this for good.

I'm going to demystify the European standard lock body, explain what those "weird numbers" really mean, and show you how to specify this hardware like a pro, the first time. We'll cover the key definitions, the two measurements you absolutely must know, how this system is fundamentally different from US hardware, and how to order a complete, functional assembly.

Simply put, a European standard lock body—also called a Euro mortise lock—is the metal box (the "case") that gets installed into a pocket, or "mortise," cut into the edge of a door.

But its defining characteristic, the one that matters, is that it is engineered exclusively to accept a Euro profile cylinder.

This immediately separates it from the common US-style cylindrical or tubular lock, which just gets installed in two simple holes drilled through the door. Frankly, the US system is built for "fast" installation, not "flexible." The Euro mortise lock is a far more robust, complex, and integrated piece of engineering.

The "standard" in its name is where the real magic is.

Unlike the US market, where every brand (like Schlage, Kwikset, or Sargent) is its own closed ecosystem, the European system is built around a high degree of interoperability. This means you can confidently pair a German-made lock body with an Italian-made handle set, knowing the critical dimensions will line up. This standardization is a key advantage, allowing for interoperability between components, a system governed by official DIN standards like DIN 18251.

Alright, listen up. This is the part everyone gets wrong. If you only remember two things from this entire guide, make it these two measurements.

If you get either of these wrong, your hardware will not fit. Period.

This one's the easy one. The backset is the horizontal distance from the front edge of the lock body's faceplate to the center of the cylinder opening (the keyhole).

This is the one. This is the specification that causes 90% of the ordering mistakes I see. The PZ, or "centers" measurement, is the vertical distance between two key points.

Don't guess. Getting the PZ and backset measurements correct is critical, and this technical guide to measuring a mortise lock provides a clear visual demonstration of the process.

Let's be blunt. For most specifiers and builders trained in the US, this is a fundamentally different way of thinking about a door. We're used to "drilling holes" in the door. The Euro system is about "cutting a pocket."

This isn't a simple "which is better" debate. It's a fundamental engineering philosophy. The US system values speed and low-skill installation. The Euro system values integration, security, and long-term flexibility.

This table breaks it down.

Here's another mistake I see all the time. A purchasing agent orders 100 lock bodies. And... that's it. They've just bought a box of expensive, useless metal.

The European standard is a component-based system. You must specify all three parts to create a functional lockset.

A European standard lock body is the high-performance "engine" inside the door; it's useless without the "key" (the cylinder) and the "steering wheel" (the handle). To complete your installation, you must source a compatible Euro profile cylinder and handle set. You can explore a wide range of architectural-grade handles and high-security cylinders designed to integrate perfectly with these professional-grade locksets.

When you send a purchase order, just writing "Euro lock" is meaningless. It's lazy, and I guarantee you will get the wrong part.

A professional specification, one that I would write, looks like this:

Here's my personal checklist. Don't order anything until you can answer every one of these questions:

The European standard lock body is not a single product, but the core of a precise, component-based hardware system. Its advantages lie in its flexibility, security, and the interoperability guaranteed by DIN standards.

In my opinion, the flexibility this philosophy gives you—like rekeying a building by swapping cylinders in 30 seconds without even taking the handle off—is something US hardware just can't touch.

It just demands precision.

If you take anything away from this guide, I want it to be those two magic numbers: Backset and PZ. Get them right, and you're the project hero. Get them wrong, and you're the one explaining the delay to the general contractor.

Now you know. Go specify with confidence.

1. What's the real difference between 72mm PZ and 92mm PZ?

One word: Application. 72mm PZ is your workhorse for interior doors—offices, apartments, residential. 92mm PZ is the heavy-hitter for exterior doors, high-security doors, and uPVC/aluminum doors, as it's almost always used with multi-point locking (MPL) systems.

2. What does the DIN 18251 "Class" rating mean? Do I need to care?

You absolutely need to care. This is a durability and security rating. A Class 1 lock is for a light-duty bedroom closet. A Class 3 or 4 lock is tested for high-frequency use (over 200,000 cycles) and higher side-load resistance, making it suitable for a heavy-traffic hospital or school entrance. If you put a Class 1 lock on a public building, it will fail, and fast.

3. Can I use a US-style mortise cylinder with a Euro lock body?

No. Absolutely not. Stop. They are fundamentally incompatible. A US mortise cylinder is a round, threaded component that screws into a lock body. A Euro profile cylinder has a specific shape and slides through the lock body, held by a single fixing screw from the side. They are apples and oranges.

4. How do I not order the wrong cylinder length?

Measure your door thickness. Then measure the thickness of your handle plates (escutcheons) on the inside and outside. The cylinder length is measured from the center fixing screw hole, outward in both directions (e.g., 35mm to the outside, 45mm to the inside, for a total 35/45 length). A properly sized cylinder should be flush, or protrude no more than 3mm. A cylinder that sticks out is a massive security risk—a thief can snap it with a simple pair of pliers.

5. What happens if I buy a 60/72 lock body but 60/92 handles?

You're going to have a very bad day. The 60mm backset will be correct, but the mounting holes will be completely wrong. The lock body is drilled for 72mm centers, and your handle is drilled for 92mm centers. They will not align. You will be sending hardware back.

6. Are all Euro lock bodies reversible for left/right handing?

Most good ones are. They have a reversible latch bolt that you can change without opening the lock case—often with a simple tool. However, you must never assume. I've seen cheap, non-reversible locks bring an installation to a halt. Always check the tech sheet to confirm it's "non-handed" or "field reversible."

7. What is a "bathroom" Euro lock body?

It's still a mortise body, but instead of a keyhole for a cylinder, it has a second square spindle hole (follower) below the handle. This allows an interior privacy thumbturn to operate a simple deadbolt. It's a more robust and, frankly, classier way to provide privacy than the little "push-pin" button you see on US residential locks.