Security level (by manufacturer)
The level of protection of the lock according to the standards of the manufacturer. The higher the number, the more reliable the model is. However, note that the levels of protection of different brands are not compatible with each other and it is appropriate to compare locks according to this indicator only within the same brand.
Shackle size
Dimensions of the shackle in a
U-lock or padlock (see "Type").
In the first case, only two parameters are usually indicated — width and length (height), most often in that order, but sometimes vice versa. However, it is not difficult to determine where what size is — the length is longer, this is due to the purpose of the lock. It usually varies from 130 – 140 to 300 mm, width — from 80 to 115 – 120 mm. A larger shackle gives more options for attaching the bike (it will “get” further and be able to cover a larger object), however, the lock also turns out to be bulky and heavy. Shackle thickness for U-locks is listed separately (see below).
But in padlocks, all three sizes are usually called, including the thickness. Here, the width and length most often differ slightly, by a couple of millimetres, although there are exceptions, with an elongated bow. Anyway, this parameter is not as important for such locks as for U-locks: firstly, hinged models are miniature by definition, and secondly, the difference in size is not particularly critical for their main purpose (shackles 20x20 and 30x30 mm are the same effectively fasten the ends of the "average" cable or chain).
Shackle diameter
The thickness of the shackle in a U-lock (see "Type").
The thicker the brace, the more difficult it is to saw through/bite, the more the lock makes it harder to steal the bike. The downside of this reliability is an increase in size and weight, and quite noticeable literally with every additional millimetre. Therefore, in most modern U-locks, the staple thickness is from 12 to 14 mm — this is considered the optimal compromise between strength and lightness.
Note that staples of the same thickness can be made from different materials, and the composition of the metal also affects reliability. Usually, the quality of the material also directly depends on the price category.
