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These are used by the United States Post Office on residential mailboxes. The delivery driver uses this lock to gain access to the whole grid of mailboxes. They are rather hard to obtain, so I figured it may be of interest to show the insides.

It's an 8 lever lock. The levers in this particular one are stamped with numbers 5, 6, 7, 8 with number 8 having no cut (i.e., corresponding to the deepest cut of the key). So I'd say it's reasonable to assume they can use depths in the range 1-8.

It's against federal law for the manufacturer to give these to anyone other than the post office (18 U.S. Code § 1704) and I think they are typically destroyed when going out of service. That's why they are hard to get. But to my knowledge, there is no law against owning them.

My understanding is also that it generally is perfectly legal to own them, e.g. if bought on ebay, but also generally people in the US are very reluctant in showing them because of possible issues. I think this is the third Arrow lock I have seen online.

Now that I'm looking at it, I see that the levers are not all the same length so that the fence would travel an extra few millimeters depending on how many gates were in the correct position. Of course all locks are going to have some manufacturing variation, but this is orders of magnitude more than I'd expect. It's extreme enough that you can easily see it in the pictures. I have no experience with lever locks. Is this common?

It might be better when the levers are at their correct position, but I doubt it drops to the range of error of other locks. The lever belly is also quite different from other locks. Probably very easily decodeable. Maybe they had a high confidence in the protection the law and the secrecy provides. At least the barrel and curtain will make life for gangsters more difficult.

The lock is legal to the the key on the other hand is a technically a federal offense. Super cool though. I have never seen the inside of one.

For those interested, here are pics of the Modified Arrow Lock (MAL) with the Medeco keyway.

Thanks for the pictures!

I assume the original lever lock is not made anymore?

just noticed a medeco cylinder in a blue USPS box in front of an office building this morning.

Yesterday, I saw a couple of Arrow locks (old style) on banks of mail boxes in the parking lot of the business park where I work. I guess they are still being used even in some large cities.

Gordon