These were lots of fun to try to figure out. There's a double horseshoe with a ring that I was able to figure out eventually. This set of two pins was the easiest to solve:
The other two were harder (free the heart, and separate the two M-shapes). My hubby spent quite a while with the M-shapes but eventually got the solution for that one from their website.
Like I've said before, they make excellent gifts. This set comes in a nice wooden box but you could, if you wanted to, split the gifts and give just one brainteaser to three different children—or adults.
They also sell two other metal brainteaser sets:
Monkey Pod Games also has tons of wooden puzzles and brainteasers, some of them less than $10. Check them out! Hey, I got to playing around with Blogger's Amazon tool and found some images for you real quick... click for more info.