The term padlocks refers to a very wide range of different types of lock. Usually this means the conventional small padlock which locks with an inverted U-shaped shackle. The quality of padlocks can vary greatly with type and cost with improvements coming from complexity of the key or combination system, the design used, and the quality of the machining. This guide will cover a few basic types of small padlock including your typical conventional keyed brass padlock, several types of combination padlock, and keyed-alike padlocks.
Keyed padlocks come in all shapes and sizes and a range of construction materials. The most common type is your simple brass padlock which is machined from a single block of brass. Padlocks which have the cylinder set in a block of sandwiched slices of galvanized or stainless steel have also become quite popular. Both are quite difficult to hacksaw through and, if you are considering a small padlock, there's really very little you can do if your potential burglar has the time and seclusion to saw through your lock. The main advantage of keyed locks is that they are, relatively speaking, difficult to pick. That being said, any cheap lock can quite literally be picked in seconds if your thief has good equipment and tooling and some rudimentary knowledge of picking techniques. Generally speaking the greater the number of pits, peaks and slits cut into the length of the blade of the key, and the greater the number of cut faces the blade has, the harder it is to pick.
One variation on these products that buyers may find to be very useful in the workplace, school, or around the home are "keyed-alike padlocks". These are where a package of multiple locks is sold together with the unique feature that they're all keyed identically: One key will open all of the locks in the set. Buyers should keep the same things in mind for these as they would with normal keyed padlocks as they are essentially the same thing.
The padlock that shows the greatest amount of variation in types is the combination padlock. There are several basic designs and, unfortunately, the majority of them are particularly vulnerable to picking. Combination locks of any sort certainly have their advantages, the most obvious of which is that since the owner doesn't even have a key it can't get lost or stolen and the lock can be opened at any time with the correct combination. From a picking point of view, this is also their biggest problem. There are three main types of combination padlock. The first is commonly found in schools on lockers, consisting of a U-shackle that locks into a padlock with a dial on the front face with 40 numbers marked on it. They also feature a normal cylinder with a simple master-key operated lock on the back. The most popular brand of this sort is Master and despite having produced this design for more than twenty years, it remains trivially easy to open these within a few minutes with no more than sharp hearing.
The second main type, Sesamee padlocks - after the most popular brand using this design, Sesamee padlocks - can be opened with no more than a flat length of steel and some know-how. A Sesame lock is shaped like your conventional padlock but rather than a keyhole, you find three or four wheels on the base with numbers 0-9 marked on each. The thing to look for here is the quality of the machining. If the lock generally feels and looks well made, with no gaps next to each of the wheels and the solid part of the lock, the safer it is. A well engineered and machined Sesamee lock is actually quite secure.
Thirdly, although not strictly a padlock, there is a combination padlock similar to the sesame locks, except the wheels are set into a cylinder, each half of which is connected to a bicycle chain. These are probably the simplest and cheapest of all the locks mentioned and they should be avoided at all costs: A six-year old can crack one in minutes.
