I bought this because it was about half the price of a real Noga. When I first opened the package and played around with it for a few minutes, it seemed to work good, but after a short while I noticed it was leaking oil on my hands and wouldn't lock up anymore. I investigated it by unscrewing the knob completely and saw that this thing locks the arms by hydraulic pressure. So I added a few drops of light weight machine oil where the knob screws in. I then screwed the knob back in. I had to experiment with the amount of oil to add. It now locks the arms very rigidly. I'm happy with it....so far.