Master Lock No 410

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Master Lock No 410

Master Lock 410 LOTO
Master Lock 410 LOTO, orange - FXE47410.jpg
Name Master Lock 410 LOTO
Manufacturer Master Lock
Lock Type Cylinder, Padlock
Lock Design Pin-tumbler
# of Components 6
Component Type Pin-tumbler

The 410 LOTO is a plastic-body pin-tumbler padlock made by Master Lock.[1] It is designed and marketed to electricians and maintenance workers who need to lock out and disable equipment while performing maintenance.

The 410 LOTO is notable as being one of few 6 pin locks manufactured by Master Lock. It has also achieved notoriety among locksport communities as a well-known practice lock for learning tension control and recognising counter-rotation while picking security pins.

Principles of operation

See Pin-tumbler (Principles of operation)

The 410 LOTO is a 6-pin core containing 5 spools and 1 lightly serrated pin[2], in random positions. The keyway is physically restricted by the plastic body to rotate only clockwise, but the core is able to rotate counter-clockwise using a tension wrench underneath the body. The lock can be permanently damaged by rotating the core 180° clockwise, as this can drop the key pins out of the lock or into the lock body.[3]

The lock is available with two possible keyways. It is not usually possible to know which a lock will come with until it is opened.

The 410 LOTO uses a ball-bearing locking mechanism to detain the shackle, making it immune to the shackle bypass techniques common on older Master Lock padlocks.

Disassembly instructions

The 410 LOTO cannot be disassembled non-destructively. However, it is possible to take it apart relatively easily, while keeping it mostly intact. The plastic lock body can be split using a tool wedged down the shackle hole in some cases, or can be cut along the seam using a rotary tool to weaken the seal.[2]


The 410 LOTO design prevents any shim bypass, either by core or by locking mechanism. However, the padlock is made of plastic and does not have a hardened shackle, and as such is vulnerable to many brute force or heat attacks. It is vulnerable to the following:


See also