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I've seen vague references to MTL "Service Keys" in the instructions that have come with certain locks. I am assuming that a service key is a key with a particular factory-determined bitting for each keyway, but I'm not sure of their purpose. Here's why I'm asking: below is a picture of three different MTL's in three different formats that came from three different eBay sellers. One of the auctions said that it came with a "service key." The others didn't mention the term or indicate anything special about the bitting. As you can see, the bitting is the same for all three locks (presumably, bitted to a/the MTL 206 keyway "Service Key"). So, does anyone know exactly what MTL service keys are, what they are used for, and why they exist? I'm starting to get very curious given that MTL's with the same bitting are starting to pile up in my collection. It also makes me wonder how many of these service key bitted locks are in use, with the users unaware of their security vulnerability! Thanks in advance for any information you can provide.

Service keys are a set biting as you properly guessed. They are for when a lock comes base pinned from the factory, you insert the service key and turn it so you can remove the plug to rekey the lock. For all intents and purposed it is the same as a 0 bitted lock.

Thank you. When viewed in that light, it seems to me that the choice of bitting actually makes MORE sense than "zero" bitting... particularly given the cost of the MTL pinning kits. The bitting appears stepped so that you get one of every size outer key pin, and one of most of the inner sizes. I would imagine that this helps to evenly replenish/maintain the pinning kits of locksmiths that regularly install these. Assuming that's the purpose, I have to say that I'm impressed at how well thought out this is.

Thanks again for the information.

If I remember correctly , the bitting for a Classic profile is A1 A2 B3 C4 D5.
For interactive , the bitting is (profile 266) A1 Z0 B3 C4 D5.
It's the same as using 0 bitting , but you get a much more evenly distributed stock of pins , even with a low amount of cylinders.

As to the possible security vulnerability , Mul-T-Lock ships the service cylinders without the C-clip in the back installed , and also without a key. It would be difficult to accidentily install them that way.

From a business point of view I doubt MTL worries about our pinning kits but then again each kit does come with a pin measurement card which allows you to measure each pin in seconds.

Now that I think about it, I have seen this stepped bitting pretty often but never gave it more thought than cool stepped bitting.

"Accidentally" is the key word (pun intended)... But the fact that I received these locks (particularly the padlock) in "ready to use" condition (with keys) suggests that it is very possible for it to happen. FWIW, I suspect that at least one of the sellers knew he was doing something wrong. I say that because someone scratched the locksmith's phone number off one of the service keys I received.

it might have a little to do with the fact they were from ebay not the manufacture. so the fact they were "Read to use" has more to do with the seller then MTL.

is that key the control key for that MTL LFIC?

i have a few of those but have never seen a picture of what the control key looks like.
but if you simply remove the blocking plate from inside the tailpiece you can use the regular key as a control.

thanks.

No, it's not quite long enough to reach that back pin... I'd imagine that you could make a control key quite easily with a little bit of solder and a normal operating key. Not sure if you've seen it yet, but I just posted a video about getting MTL LFIC/FSIC cores to control. https://www.youtube.com/watch?v=AuE3RtOn9IA