Master Lock Black Outdoor Key Lock, Standard Weather Resistant Padlock with Cover, Keyed Alike Padlocks for Lockers, Fences, Sheds, or Other Equipment, 2 Pack, 131T

Why I picked these locks

I wanted a small, keyed-alike set I could spread across a few low-risk spots: a gym locker, a compact shed hasp with tight clearance, and a toolbox I toss in the truck. The Master Lock 131T two-pack hit that brief on paper—compact body, shared keys, and a weather-resistant design that wouldn’t look corroded after a season outdoors. After several weeks of daily use and a couple months of one unit living outside, I’ve got a good sense of what these locks do well—and where they’re not the right pick.

Build and design

The 131T is a compact, vinyl-covered aluminum padlock with a steel shackle. The body is about 30 mm (1-3/16 in) wide, and the shackle is roughly 3/16 in diameter with modest clearance (about 5/8 in vertical, 9/16 in horizontal). In practice, that size does two important things:

• Fits hardware that many “standard” padlocks don’t, like tight locker hasps, small shed loops, and toolbox latches.
• Limits security by simple physics; the shackle isn’t thick or long, so it’s not intended to fend off cutters or heavy prying.

The vinyl jacket is more than cosmetic. It keeps the body from scuffing painted or powder-coated hardware, adds grip when your hands are wet, and slows corrosion in messy environments. The shackle is steel; it’s durable enough for day-to-day abuse, but it isn’t a heavy hardened alloy. Expect “basic deterrent,” not “serious cut resistance.”

Internally, you get a four-pin cylinder and a dual locking lever. The dual lever helps resist shimming at the shackle. The four-pin core is simple and serviceable—smooth to operate, not finicky in cold weather—but it’s not designed to be pick-resistant in any meaningful way. For the intended use cases, that tradeoff is fine.

Two identical keys are included and operate both locks. The shared-key convenience is the star here; it’s nice to carry one key for multiple doors, and the color-matched key heads make them easy to spot on a ring.

Everyday use

Out of the package, both locks operated cleanly—no gritty feel, no sticking, and consistent shackle pop. The key action is positive, with a short, predictable turn to unlock. I had no trouble aligning the key by feel, which is helpful on dim job sites or in cramped spaces. The compact body makes it easy to maneuver the shackle into small hardware where bigger locks simply won’t fit.

A few practical notes from daily use:
- On a gym locker, the small shackle diameter slides through narrow hasps without binding, and the vinyl jacket keeps the door face from getting chewed up.
- On a small shed with awkward loop geometry, the short shackle clearance is useful—it closes securely without leaving a lot of exposed shackle to pry on.
- On a steel toolbox, it stood up to plenty of rattling around in the bed of a truck without the spring weakening or the keyway getting fouled.

I prefer to give new padlocks a shot of dry PTFE lube; with that, the action stayed smooth through a stretch of rainy days and a few sub-freezing mornings. It’s not essential here, but it’s cheap insurance against grit and moisture.

Security reality check

This is a compact, convenience-first lock, and Master Lock doesn’t pretend otherwise. The four-pin cylinder and dual locking lever provide baseline resistance to casual shimming and opportunistic tampering, but this is not a high-security device. With a 3/16 in shackle, it won’t withstand dedicated attacks with larger bolt cutters, and a practiced picker won’t struggle with the core.

Where it makes sense:
- Indoor lockers and cabinets
- Toolboxes and storage totes
- Small shed hasps and garden gates that mainly need to be closed and discouraged from casual snooping
- Cases and containers where you need non-TSA locks that only you control (for example, a hard-sided firearm case checked with an airline)

Where it doesn’t:
- Chains, hasps, or gates that see real theft pressure
- Outdoor installations that expose the lock to salt spray or heavy corrosion without maintenance
- Thick or oversized hardware; the shackle diameter and clearance limit compatibility

If you need a tougher option, step up to a thicker, hardened shackle and a more robust core. You’ll trade the small size that makes the 131T so handy, but you’ll gain meaningful cut resistance.

Weather performance

One lock lived outdoors on a shed for a couple months, catching rain and morning dew. The aluminum body and vinyl jacket came through looking fresh, and the cylinder kept turning with just that initial dab of dry lube. The steel shackle held up fine; I wiped it down once when I noticed light spotting after a particularly wet week, and it didn’t progress.

There’s no sliding keyway cover, so dirt and water can find their way in over time. A protective cap would be nice, but it’s not common at this price or size. If you plan to leave the lock outside long term, a quarterly routine helps:
- Blow out the keyway with compressed air.
- Add a small shot of dry PTFE or graphite; avoid heavy oil that attracts grime.
- Wipe the shackle down after storms, especially in coastal areas.

In short: weather-resistant, not weatherproof. For inland, general outdoor use, it’s perfectly serviceable. For marine environments or winter road salt, I’d look to a stainless or brass-bodied marine lock.

Fit and compatibility

Measure your hardware. The 3/16 in shackle is slim, which is great for tight hasps, but the short vertical clearance means it won’t bridge thick or oddly offset loops. On a compact shed door with narrow clearance around the hasp, the 131T did what a standard 40–50 mm lock couldn’t—fit cleanly without binding or rubbing the door frame. On a typical chain link gate latch or a chain, this lock is usually too small or leaves too little bite to be useful.

As a keyed-alike two-pack, the value is best when you know exactly where they’re going. I assigned one to the shed and one to a toolbox; carrying one key for both is a small daily win.

What I’d change

• A keyway dust cover would improve long-term outdoor reliability.
• A hardened shackle option in the same form factor would extend its utility without sacrificing size.
• Offering a longer shackle variant would make it more versatile for bulkier hasps while keeping the keyed-alike convenience.

Pros and cons

Pros:
- Compact body and slim shackle fit tight hardware where larger locks won’t
- Keyed-alike convenience with two included keys
- Smooth, consistent operation out of the box
- Vinyl-covered aluminum body resists scratches and general corrosion
- Good value for low-risk indoor/outdoor tasks

Cons:
- Limited security; thin, non-hardened shackle and basic four-pin core
- No keyway dust cover
- Short shackle clearance limits use on thicker hasps and chains
- Not a great pick for harsh marine environments without upkeep

The bottom line

The Master Lock 131T is a smart, no-fuss choice for low-risk locking needs where size and convenience matter more than brute security. It’s easy to fit, simple to use, and the keyed-alike two-pack streamlines everyday life. The weather-resistant build holds up well with minimal maintenance, provided you’re not parking it in salt spray or neglecting it for years.

I recommend these locks for lockers, toolboxes, compact shed hasps, and travel cases that need user-controlled locks. I wouldn’t use them on high-value targets, exposed chains, or anywhere a determined attack is likely. Used in the right context, they’re reliable, tidy little workhorses that do exactly what they’re designed to do—and not more.