The jack on the right is the one I will use on the model. As you can see it is significantly smaller than the test jack, (70% of the size) on the left. It also is made of brass, but with a few machined aluminum parts too. Furthermore it has a pattern cut into the top pad that the larger one does not have.
It also works the same way as its big brother.
There is a fork on the handle that fits into the receiver. You can see the knurling I put on the handles too.