Is the Master Lock 6121 worth it over a basic padlock?

Yes, if the lock sits outdoors or on a commercial site. The boron alloy shackle, pick-resistant cylinder and weather cover cost more than a brass padlock but resist cutting, picking and corrosion far better.

Can I get it keyed alike to my other locks?

The standard 6121 ships keyed different with 2 keys. Keyed-alike versions are sold as the 6121KA, and special key numbers can be factory ordered, usually with a 2-3 week lead time.

How does it hold up in winter weather?

The Weather Tough cover is designed to keep water, ice and dirt out of the cylinder and body. Owners report it working through freezing and wet seasons, though the cover itself can crack after years of sun exposure.

What size hasp does the shackle fit?

The shackle is 5/16 in in diameter and 1-1/8 in tall inside, with a 7/8 in width. Check that your hasp opening clears 5/16 in and has at least 1-1/8 in of vertical room.

What comes in the box?

One padlock and two keys. It is keyed different and random, so the keys will not match other Master Lock padlocks you own unless you order a keyed-alike model.

When is the price lowest?

The best new price was $24.99 at Amazon as of November 5, 2026. Padlock prices move little, but checking the price history before buying shows whether a store is running above its usual level.

Where is the Master Lock 6121 Stainless Steel Padlock cheapest?

At Amazon, for $24.99, 26% under what the other stores charge, as of our latest check.

Where can I buy the Master Lock 6121 Stainless Steel Padlock?

6 stores we checked sell it, including MrLock.com, eBay, Anderson Lock, Walmart, Motion.

Master Lock 6121 Stainless Steel Padlock

Best price now

$24.99at AmazonObserved at 8:21 AM

26% under what the other stores charge

Compared across 6 stores. Prices are checked against each store and labelled with when.

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Our take on the Master Lock 6121 Stainless Steel Padlock

The Master Lock 6121 is a commercial-grade keyed padlock built for outdoor and industrial use. It pairs a 2-1/8 in heavy steel body with a 5/16 in hardened boron alloy shackle and a Weather Tough cover that seals out water, ice and dirt. The rekeyable 5-pin cylinder with spool pins is hard to pick, and the dual ball-bearing locking resists prying. At $24.99 at Amazon as of November 5, 2026, it sits at the low end of its recent range across the 6 stores that list it new.

What reviewers say

Owners of the ProSeries line generally treat it as a dependable outdoor lock that holds up through winters and wet conditions. The pick-resistant cylinder and rekeying option draw the most praise.

Pros

Survives rain, snow and salt air without seizing
Cylinder is smooth and hard to pick
Rekeyable to match existing keys
Solid feel and tight shackle fit

Cons

Cover can crack with heavy UV exposure
Short shackle limits some hasps
Keyed-different only out of the box

About the Master Lock 6121 Stainless Steel Padlock

Master Lock 6121 KD

Product Details

The Master Lock No. 6121 ProSeries® Weather Tough® Covered Laminated Padlock features a 2-1/8in (54mm) wide heavy steel body to withstand physical attack and a 1-1/8in (29mm) tall, 5/16in (8mm) diameter hardened boron alloy shackle for superior cut resistance. The exclusive cover protects this padlock from harsh elements & a high security, rekeyable 5-pin cylinder with spool pins is virtually impossible to pick.

Product Features

Ideal for harsh outdoor conditions - exclusive Weather Tough® cover protects lock from water, ice, dirt and grime

ProSeries® Padlocks are designed for Commercial/Industrial applications

2-1/8in (54mm) heavy steel body withstands physical attack

1-1/8in (29mm) tall, 5/16in (8mm) diameter hardened boron alloy shackle for superior cut resistance

Dual ball locking mechanism resists pulling and prying

High security, rekeyable 5-pin cylinder with spool pins is virtually impossible to pick

Padlock supplied keyed Different/Random with 2 keys.

Click on Related Products for a listing of our stocked keyed alike numbers for the Master Lock 6121KA. Special order locks are available - if your key number is not listed, select the Factory Order Keying Option(please allow 2-3 weeks for shipping) or quick ship(extra labor included in price for keying)