Gary's Open Lock (also called the Transparent Lock) is just what the name says; its a naked lock with everything (well almost everything) showing. Its a pretty large lock measuring about 12 cm from the bottom to the top of the shackle and roughly the body is about 2 cm thick. The lock is made of aluminium while the shackle is forged steel. Gary doesn't make many of these because its very difficult to manufacture and so the numbers available are usually very limited and consequently, very expensive as well. In case you didn't know, the Lunatic Lock, which is commercially available was also designed by Gary Foshee.
The Open Lock can best be described as a "sequential discovery" puzzle. Meaning that you have to open the Open Lock (no pun intended) with nothing else but tools and implements that come with the lock. No external tools are permitted. In the case of the Open Lock, there is only the T-shaped hex key, instead of a key.
The Open Lock shows its insides (of course it does!). And you will note that the shackle is locked in place by two horizontal bars, a thin one nearer the top (visible in the bottom photo) and a thick screw threaded rod at the bottom. It is obvious that these two rods must give way for the shackle to be pulled upwards and freed.
Here is where the sequential discovery part of the puzzle is. The solve is not difficult (certainly not the level of difficulty of the Popplocks), but tricky with some surprises (and A-ha moments). One has to use whatever tools available and do various tasks along the way to finally get the shackle unlocked from the body. Although it takes about seven steps to remove the shackle, it still takes a fair amount of time to complete the entire solve and to re-assemble everything.
Overall a very fun and entertaining puzzle lock which does not disappoint. Experienced puzzlers would have no problem with it. Unfortunately it seems that they are only available every couple of years and in very small numbers, very much rarer than Popplocks. So the only way to is to buy privately or through auctions, if at all they show up during the latter.