The chain and lock are both very strong. Got a bit of weight to them which we like but not too much.The lock itself can be used without the chain as a disc lock. However, I use mine with the chain as I have a separate disc lock.Test of strength (for lock) the other day I couldn't get the lock open and was getting very frustrated. So I resorted to trying to beat the living hell out of it with a hammer and tried to cut it.Other than a few scratches it was fine. And then I realised I was using the wrong keyBut it is strong and i'd definitely buy it again