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  1. King Pin Locks
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  3. Aluminum
  4. Keyed Unique
  5. Red
MasterLock High Security King Pin Lock

MasterLock High Security King Pin Lock

Item # ML387
Our Price: $145.83
You Save: $39.38
King Pin Locks
Shipping Weight: 7 lbs
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Fastest Shipping and Great prices for MasterLock High Security King Pin Lock. Read our customer reviews of Master Lock king pin locks. Call 1-800-940-8924 for expert service or order your king pin locks part number ML387 by Master Lock online at
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  • Reviews (29)
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  • Videos (1)
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Master Lock King Pin Locks - ML387

  • Aluminum
  • Master Lock
  • Keyed Unique
  • Red


  • Secures the king pin on fifth wheel trailers, semi-trailers and RVs
  • High grade aluminum provides high security
  • Resistant to bolt cutters
  • Red body alerts that lock is attached

387 Masterlock High Security King Pin Lock

Video of MasterLock High Security King Pin Lock

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for MasterLock High Security King Pin Lock Review

What's up everybody, it's AJ with Today, we're gonna be checking out this Kingpin Lock from Master Lock. It's gonna go right up in here, on your kingpin, lock in place with just the easy turn of a key. Let's check it out. The whole base made out of a very solid aluminum, it's also pretty thick so you can't just put a bolt cutters on there and cut this off. The lock is actually inside little room too so you can't access the front part of it, all you do to unlock it is just use your key, turn like that, now it's unlocked, and you pull that out, and then you can take it off.

Now, one issue we do notice is when you pull back on this to release it, it should release and come right down here, but it seems like the handles. go in a little bit and they are on the fifth or the kingpin itself. So, you have to kind of pry out on them a little bit to get this to come out. Like that. Take a look at the inside, you can see what the problem was there.

The handles, you can see the ends coming in, we're grabbing onto that lip of the kingpin. So, when we unlocked it and pulled this back, it should have dropped down. But then we had to pull and pry these apart just a little bit enough on each side for it to slide-off there. The diameter of the lock is gonna be three inches across, and then in between the two spots on the handle is gonna be 2 and 5/8 inches. It's also bright red so you can see it from a mile away, just, you know, a better way to deter it if somebody's walk around at the RV park, think about messing with one of these, they'll see the big bright red and the flag that's on there, and that'll kind of deter them and they'll just go to the next one that doesn't have a lock on it.

But I do also like that it has the handle, that way you can hold it because if you saw on that kingpin, it's covered in grease, and so there's all a bunch of grease on the inside now. So, instead of holding it with my hands there and getting my hands all greasy, I got the handle, my hands are up and out of the way and I don't have to clean up. Overall, I think this gonna be a nice heavy duty lock for you. And on your kingpin, it's gonna lock that up and just I know that it's gonna hold up, I'm not worried about somebody taking a pry bar to it and breaking off really easily. No lock is perfect, but this is gonna be good to keep it locked up nice and tight.

Well, I think that does it. Thanks for hanging out and I hope this helped..

Customer Satisfaction Score:

Customer Reviews

MasterLock High Security King Pin Lock - ML387

Average Customer Rating:  4.9 out of 5 stars   (29 Customer Reviews)


Probably overkill when parked in the RV storage lot, but I'll feel better while the RV is unattended out at some dispersed camping location. I bought MasterLock because I trust the brand. The unit seems solidly built. It coupled to my king pin without any issues.


This kingpin lock is very well made. It has a thick steel collar with an integral Master lock securing a pin that prevents theft. The only reason I am giving it 4 stars is that I cannot use it with a Pullrite Superglide hitch capture plate installed on my 5th wheel.


Easy to put on and off. So far we still have our trailer. Excellent deterrent


It protects mu $125k Toy Hauler. Love it, yes on recommendations .


Great well made product, fast delivery arrived on the date that was told it would. Will be great having a peace of mind not worrying about RV when we're not there. Highly recommend this product for anyone with a RV. Thanks for great Service and product.


Product works great but has not held up as great against the weather. Handle has pitted pretty bad. It functions fine as long as you keep it lubricated. Would recommend it to anyone who has to store their fifth wheel


I'm always happy with etrailer, and the lock I received. I think it would be a great idea to make the handle out of stainless steel. Mine has rusted in this passed year. If no rust, 5 stars.


Very solid lock that I'm sure will deter anyone from even trying. i was a little surprised that the wrapping around the handle is not rubber; it's more like a sheet of vinyl wrapped around several times. I guess it's ok, but will have to wait to see how durable it is. Overall, my main requirement was for a solid heavy duty lock, and this fits the bill.


Great way of getting to lock(vandalize) when placed on king pin..Able to leave trailer secured and have mental piece while I'm away around town.


Very sturdy, yet simple design. I considered many other types of these locks but I couldn’t be happier with my choice for selecting this one. Aside from being extremely functional for its intended purpose, its “look” alone is enough to discourage most thieves…or at least make them pass you by for a less secured trailer.


Solid product. Color really helps avoid head collisions when accessing cargo area.

Mark K.


Holding up well. Daunting looks probably wards off plenty of evil doers :-


We use our lock constantly! We have never had an issue. It is compact, easy to use, and most importantly gives us peace of mind! Great product and highly recommend it!


Not used yet But I read enough that tells me that my fifth wheel will be where I leave it


Nicely engineered, easy to install and remove, handy carrying handle, easy to see your RV is secured - great product!


Lock appears to be robust and the difficulty of defeating it quite high. It was very easy to install and I am hoping that it will act as a great deterrent.


Love Love Love this company. Every time I order from them, My order has been on time or early. Highly recommend this Company. CLASS A...


Heavy Duty! Just hope it fits. The fifth wheel is about 260 miles from me!


The product works just as advertised, very happy with it

Karron W.


It is awesome


Great product to use and is of very high quality. I feel very comfortable securing my trailer with this King Pin lock. My drivers have used this for many situations when we had to drop the trailer in an area to get something fixed so we could get the tractor in a tight spot.


Great product at a great price. If you got a fifth wheel you don't want stolen, this is the lock for you. The only way anyone is getting this thing off without a key is a locksmith or a cutting torch. This thing is built to the extreme. The collar is almost an inch thick steel and completely encompasses the padlock.


It’s been a year and this thing is just as solid as the day I got it! Absolutely love this lock! I highly recommend it, it’s worth every penny!


Solidly built and easy to use as advert ised


Received my product and all went well. Except for UPS holding on to it for 2 and 1/2 days then delivering at 8PM at night


Just as advertised and easy to use. Pe rfect.


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See what our Experts say about this Master Lock King Pin Locks

  • What is the MasterLock King Pin Lock Made From and How Much Does It Weigh
    The MasterLock # ML387 is made from high grade aluminum and weighs roughly 7-lbs. You won't have any issues fitting this lock over a king pin with a lube plate either, since it does leave some room at the top and doesn't sit flush against the pin box. I've attached one of our customer photos that shows this installed.
    view full answer...
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  • Are There 5th Wheel King Pin Locks
    There are king pin locks, yes, and the best option for the most protection is one from Master Lock: - MasterLock High Security King Pin Lock # ML387 The # ML387 won't shear from bolt cutters and totally encompasses your king pin for complete security. Put this on your king pin and your 5th wheel trailer is absolutely going to stay put.
    view full answer...
  • Availability of Keyed-Alike 5th Wheel King Pin Locks
    We can offer you several choices in a 5th wheel king pin lock that can be ordered in multiples that are all keyed alike but Master Lock King Pin Lock # ML387 is not among them. We offer our aluminum King Pin Lock # e98896. It can be ordered in any quantity you need with all locks keyed to the same key. Just select the keyed alike option from the drop-down menu tool and then select your quantity. There is a modest charge for this service.
    view full answer...
  • Will Master Lock 5th Wheel King Pin Lock Fit 2015 Keystone Alpine 3010RE
    Based on my research, the Masterlock High Security King Pin Lock, part # ML387, will work for your trailer. As long as the king pin on your 2015 Keystone Alpine 3010RE is a standard 2 inch diameter king pin, the # ML387 will work well for you. I have attached a review video of this lock for you.
    view full answer...
  • Recommendation For A Gooseneck Trailer Lock
    The MasterLock High Security King Pin Lock, Item # ML387, is not compatible with your Big Tex Gooseneck Trailer. The MasterLock is for fifth wheel trailers and will not work with gooseneck trailers. We do have some gooseneck locks like the the Blaylock EZ Lock Gooseneck Coupler Lock, Item # BLTL-50-40D, that will work if you have a Bulldog, Stallion, Superior, or T.E.M. coupler. If this will not work for you, let me know which coupler you have and I will look for other options.
    view full answer...

Do you have a question about this King Pin Lock?

Info for this part was:

Employee Andrew K
Installed by:
Andrew K
Employee Cole B
Installed by:
Cole B
Employee Jacob T
Video Edited:
Jacob T
Employee Wilson B
Updated by:
Wilson B
Employee Aidan B
Video by:
Aidan B

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