The best quality and construction of all three models from this company are very good. The S is the simplest; the angle on the arm is not adjustable. The 2 has three settings, and the 3 is adjustable micro-metrically with a knob at the back, which is much more convenient. The base is separate and is the same for all three. Be careful, it is sold separately, but if you add the price of the base and the mechanism, you will still get it at the same price. The mechanism is the same for all cars; the only thing that changes is the base. However, the weight that is mentioned that it can withstand under pressure is incorrect; none of the models can withstand 50 or 80 kg as stated. The mechanisms are very sturdy, but their bases do not hold, so never support all the weight on them. Otherwise, it is a very, very good quality product. The model 3 works for me; it is larger in length and has more adjustable positions with the knob. It always adjusts the angle of the arm, not the height, and in both models 2 and 3, the S is not adjustable at all; it is fixed. I highly recommend it; after extensive research I did, I have not found anything better