bing tracking image
  1. Padlocks
  2. Master Lock
  3. 3/8 Inch Diameter
  4. Hidden Padlock
Master Lock Hidden Padlock - 3/8" Shackle Diameter - Chrome

Master Lock Hidden Padlock - 3/8" Shackle Diameter - Chrome

Item # ML6271
Our Price: $40.22
Orders above $50 qualify for Free Shipping
Shipping Weight: 1.81 lbs
In Stock
Padlocks ML6271 - 3/8 Inch Diameter - Master Lock
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images


Need help with installation?
Locate installers near me
This high-security, hidden-shackle padlock features a 2-7/8" wide lock body that conceals the 3/8" diameter shackle to prevent theft. Great Prices for the best padlocks from Master Lock. Master Lock Hidden Padlock - 3/8" Shackle Diameter - Chrome part number ML6271 can be ordered online at or call 1-636-306-4830 for expert service.
  • All Info
  • Reviews (2)
  • Q & A (0)
  • Videos (1)
  • Photos
  • Why etrailer?

Master Lock Padlocks - ML6271

  • 3/8 Inch Diameter
  • Hidden Padlock
  • Master Lock

This high-security, hidden-shackle padlock features a 2-7/8" wide lock body that conceals the 3/8" diameter shackle to prevent theft.


  • Reinforced, 2-7/8" wide lock body conceals shackle to prevent theft
  • 3/8" Diameter shackle on back of lock body
  • Zinc die cast lock body for durable exterior
  • Boron alloy shackle for increased strength
  • Chrome color

Master Lock Hidden Shackle Lock

Master Lock Puck Lock


  • Overall lock width: 2-7/8"
  • Shackle dimensions:
    • A: 3/8" (10mm)
    • B: 19/32in (15mm)
    • C: 1-23/32in (44mm)

6271 Master Lock - 2-7/8" Hidden Shackle Puck Lock - 3/8" Diameter - Chrome

Video of Master Lock Hidden Padlock - 3/8" Shackle Diameter - Chrome

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

Video Transcript for Review of Master Lock Padlocks - Hidden Padlock - ML6271

Ellen: Hey everybody, it's Ellen here at, and today we're going to be taking a look at the Master Lock Hidden Padlock. This is going to be a very hard to remove padlock for any would-be thieves. But it's also going to keep everything secure for you.It's made of a durable zinc die-cast lock body, still have a very durable exterior. And then the shackle is made of a boron alloy, so it's going to inaudible 00:00:30 some increased strength. It comes in this nice shiny chrome color, so it's highly visible, easy to spot from across the parking lot or across the way, so people know that your stuff is locked up.Our lock body is reinforced, helps to conceal that shackle and make it pretty much impossible to cut off. As long as you can't get access back to that shackle portion, it's pretty hard to remove it if you don't have the key.

It comes with two keys to get that shackle taken out.If this ever becomes damaged, you can actually replace that just by removing that little bolt there. And there are replacement shackle kits available here at You can also pick up a hasp to go with this to mount onto your trailer, maybe mount onto your workshop, anything that you want to lock up with this lock. That part number that you can find here at is ML-770. And that will mount that up.As far as the dimensions with this, overall, it's two and seven-eighths inches in diameter.

At the thickest portion, it's about 1.5 inches wide. The narrower portion here on the other side, it's about 1.25. The shackle measures three-eighths in diameter, or 10 millimeters. The distance of this little cutout here, top to bottom, is about 19 and thirty-seconds, or just about five-eighths. And then the width will be one and 23 thirty-seconds inches, or pretty close to one and three-quarter.Overall, I think this is going to be a great security option for anything that you want to keep locked up.

And that's going to do it for our look at the Master Lock Hidden Padlock.

Customer Reviews

Master Lock Hidden Padlock - 3/8" Shackle Diameter - Chrome - ML6271

Average Customer Rating:  5.0 out of 5 stars   (2 Customer Reviews)

This high-security, hidden-shackle padlock features a 2-7/8" wide lock body that conceals the 3/8" diameter shackle to prevent theft.


Great lock for doors on Semi trailer. Should work with various hasps too.



See what our Experts say about this Master Lock Padlocks

  • How Does Master Lock Hidden Padlock # ML6271 Lock
    We don't have a picture of the backside of the Master Lock shackle lock part # ML6271 (yet) but I can describe to you how it works. Basically there's a cut out section on the backside that has a recessed and retractable 3/8 inch pin that would fit through a hole when locked. Since this pin is recessed it's basically impossible to attack from a thieves point of view.
    view full answer...
    Image 1 for
  • Recommended Padlock For Areas With High Amounts Of Vandalism And Or Theft
    The "hidden" in the Master Lock Hidden Padlock # ML6271 is referring to the shackle/bar being fully hidden from view and is completely inaccessible when the lock is attached and secured. This makes it significantly more difficult to remove than a standard lock and is highly recommended. Especially if you are seeing a lot of vandalism and or thefts in your area. I do have to mention, though, that with the correct skills, time, and patience, no lock is unpickable. However, this will definitely...
    view full answer...
  • Can the MasterLock Hidden Padlock Be Ordered Keyed Alike
    I may have a solution for you, but the Master Lock Hidden Padlock part # ML6271 cannot be ordered keyed alike. However, we do have some heavy duty padlocks with a 3/8" shackle that can be keyed alike that can provide a comparable solution. I recommend looking at the Master Lock Laminated Steel Padlock- 1-15/16" Wide - 3/8" Shackle # ML312KA, which is also a durable padlock option, but doesn't have the hidden design for the added layer of theft protection. This is available to keyed alike...
    view full answer...
  • Can Puck Lock Be Used with Blaylock EZ Lock Trailer Coupler Lock # BLTL-33
    The Blaylock EZ Lock Trailer Coupler Lock # BLTL-33 is designed to work perfectly with a standard padlock, but I think the typical opening size on the back of a puck lock will be a bit too small to fit over the end of its pin/shank. The pin/shank on this lock has a 3/4" diameter, while for example the opening on the Master Lock Puck Lock # ML6271 we have available has a height of just 19/32", which wouldn't allow it to mount over the pin. Your best option is going to be with something...
    view full answer...

Do you have a question about this Padlock?

  • Why

    At we guarantee:
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate padlock information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Employee Tyler C
Edited by:
Tyler C
Employee Jameson C
Expert Research:
Jameson C
Employee Kathleen M
Video Edited:
Kathleen M
Employee Erin H
Written by:
Erin H

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

Product Experts Available Now!
Call 1-636-306-4830