The DCL1/J3 is Squire’s portable chain lock. At 1.5kg it's fine to stuff this one into your backpack as well as use it at home, and it looks to the potential thief like it’s going to be a tough cookie to break.
The padlock is a clever little round design which makes it difficult to attack. The locking bar (shackle) curves and the key slot for it to slide over the links is minimal, meaning that once the chain is in place there's so little shackle showing that it's hard to cut through. The payoff is a bit of fumbling when trying to secure your bike.
The lock mechanism is very resistant to attack, and is bump resistant – by that we don't mean jolting it but using a using a specially designed key that will bump the pins into an unlocked position, kind of like lock picking for the lazy.
However, the material itself isn't up to the job. The alloy steel links could be compressed and cut by our short bolt croppers in just 35 seconds.
At £40 it’s a reasonable product but we wouldn’t recommend this on price alone as there are better locks available for around the same money.