Master Lock No 1

= Master Lock No. 1 =

The No. 1 is a pin-tumbler padlock made by Master Lock. The No. 1 uses a laminated padlock body with an internal key-in-knob cylinder. The inner cylinder uses four pin stacks and does not use any security pins. The No. 1 is one of the most common low security padlocks used in the United States.

Principles of operation
The M1 cylinder is a pin-tumbler lock with 4 pin stacks. It does NOT contain any security pins unless otherwise modified.

The No. 1 padlock uses the M1 key blank, but also can be made with a slightly different key profile. This change in profile helps to stop people from making copies of keys they shouldn't have.

A standard Master No. 1 padlock can be opened with a key both clockwise and counter clockwise, but due to a shrouding on the commercial series of this lock it can only be opened clockwise and makes picking it counterclockwise require TOK tension.

Disassembly instructions
The No. 1 cannot be disassembled non-destructively. To disassemble it, the rivets that hold the laminated body together must be removed and each layer removed individually. The inner cylinder itself can be disassembled in the same manner as a traditional pin-tumbler lock:

Notes
 * The No. 1 cylinder requires a small diameter plug follower.

Vulnerabilities
The No. 1 is vulnerable to a wide range of attacks. The reduced pin tumbler count and poor manufacturing tolerances makes it an easy lock to pick. It's commonly given to locksport beginners as a "confidence lock"; a lock that is easy to open and inspires you to continue picking. The No. 1 may be vulnerable to one or more of the following:


 * Lockpicking
 * Key bumping
 * Impressioning
 * Decoding
 * Bypass
 * Destructive entry