Well, maybe not impossible, but Impossible Lock (stainless Steel version) is a seriously difficult puzzle.
A specially constructed stainless steel padlock, 106 mm long and weighing 635 grams, this is a very solid construction, and is beautifully made. A real piece of precision engineering. And it does not give up its secrets easily!
It comes with a key, and also a small implement with a point at one end.
There are a number of separate steps needed in order to unlock this puzzle. One could spend quite a while on this one. Fortunately it also comes with a set of instructions!
They used to sell a brass version of this lock, at a slightly cheaper price. This stainless steel model is a new version from the designer, and is one of a limited run of 100 locks. This lock is marked on the back with its unique number. Available for £159.99 [$254.38] (Excluding VAT at 15%) via Grand Illusions.