Master Lock Pro Series Hidden Shackle Padlocks Keyed Alike 6271NKA-3

In this review of the Master Lock Pro Series Hidden Shackle Padlocks keyed alike set, the bottom line is straightforward: this three-pack is for anyone who needs heavy-duty, commercial-grade security with the convenience of multiple locks opening with the same key. The set ships with six keys and a hardened diecast zinc body that resists corrosion, and the standout feature is the BumpStop Advanced Cylinder Technology which specifically defends against lock bumping attempts. For enclosed trailers, gates, vending machines, and industrial applications where a tough, compact padlock matters, this set delivers consistent protection and value.

Key Features

• Keyed Alike Convenience: Three locks operate with the same key, simplifying access when multiple doors or points need the same key control.
• BumpStop Technology: The advanced cylinder uses a reverse rake driver pin and tight chambers to resist bumping and prevent unauthorized cylinder rotation.
• Hardened Body: The reinforced zinc diecast body provides corrosion resistance and durable impact protection for long-term outdoor use.
• Bolt Cutter Tough Shackle: The fully shielded hardened boron alloy shackle is designed to resist cutting and prying attempts common in commercial settings.
• Serviceable Cylinder: The removable high security 6-pin cylinder allows replacement or repinning for key control changes or maintenance.

Who It's For

This set is ideal for tradespeople, fleet managers, and anyone securing enclosed trailers, gates, vending machines, or industrial enclosures who wants a heavy-duty lock that is keyed alike for convenience. The robust build and anti-bump design suit outdoor use and high-risk access points where durability and attack resistance matter.

Those who need an ultra-lightweight or decorative padlock, or who require electronic or keyed different solutions, should look elsewhere. Also, buyers who require very long shackles or nonstandard dimensions should confirm fit before purchase, since this set is a compact, shielded design.

Pros & Cons

Pros

• Solid build quality and corrosion-resistant zinc body make these locks durable in outdoor and industrial settings.
• BumpStop Advanced Cylinder Technology provides meaningful resistance to lock bumping attempts.
• Keyed alike set with six keys reduces the need to carry multiple key variations for common access points.
• Hardened boron alloy shackle and shielding make cutting and prying far more difficult.

Cons

• Some customers reported fit issues or keys sticking occasionally, so a small minority may experience key or fitment problems.
• The compact, shielded shackle may not suit applications that require a longer shackle reach.

Specifications

Set	3 keyed alike padlocks with 6 keys
Body Material	Hardened diecast zinc
Shackle	Fully shielded hardened boron alloy
Cylinder	Removable high security 6-pin cylinder
Technology	BumpStop Advanced Cylinder Technology
Dimensions (A x B x C x Width)	3/8 in x 19/32 in x 1-23/32 in, Width 2-7/8 in

Our Verdict

The Master Lock Pro Series hidden shackle keyed alike set is a practical, heavy-duty choice for commercial and industrial needs where keyed alike convenience and resistance to bumping and cutting are priorities. It offers excellent build quality and value for securing trailers, gates, and vending machines, though buyers should confirm the shackle dimensions for specific fit requirements.

Frequently Asked Questions

Are these locks really keyed alike?
Yes, the set is sold keyed alike so all three locks operate with the same set of keys included, though a small number of users reported inconsistencies on individual units.

Does BumpStop prevent all bumping attacks?
BumpStop Advanced Cylinder Technology greatly reduces the transfer of force from a bump key and blocks cylinder rotation, making bumping far less effective than on standard cylinders.

Can the cylinder be changed or rekeyed?
Yes, the lock features a removable 6-pin cylinder that can be replaced or repinned for key control changes or maintenance.